Conservation Action Plan for the Rock Hewn Churches in Lalibela (Ethiopia) by Zeb89 Zeb89

World Monuments Fund CONSERVATION ACTION PLAN FOR THE ROCK HEWN CHURCHES IN LALIBELA Team Leader Pietro Laureano

SEPTEMBER 2008

IPOGEA International Centre on Local and Traditional Knowledge www.ipogea.org

TEAM AND EXPERTS INVOLVED IN THE PRESENT STUDY: Pietro Laureano – Team Leader Debora Giorgi - Conservation architect and assistant of Team Leader Ugo Tonietti – Structural Architect – Professor of Structural Mechanic – University of Florence Italy Luisa Rovero – Structural Architect - Professor of Structural Mechanic – University of Florence Italy Fabio Fratini – Geologist – Expert in conservation of Stone materials – CNR – Institute for Conservation and Enhancement of Cultural Heritage - ICVBC – Florence -Italy Riccardo Sabbadini – Geologist – GIS expert

Marcella Isola – Architect – GIS expert Mezemir Abye – Engineer and UNESCO Local Expert Massimiliano Burgi – Architect and Designer Andrea Mancuso – Architect –IT and GIS expert Einat Banay –Assistant Katherine Infantino – Logistic, organization, Translations Astier Ogbai – Translator from Amharic

Acknowledgements We would like to express our most sincere thanks for the contribution offered playing their professional role and for the advices given during the missions to: Francesco Bandarin Director of World Heritage Center - UNESCO Gaetano Palumbo WMF - Archaeological Conservation Director for Africa, Europe, the Middle East and Central Asia Nada Al Hassan Programme Specialist - World Heritage Centre - Culture Sector UNESCO Hirut Girma UNESCO Officer at Addis Abeba Michel Goutal ICOMOS expert And special thanks to Silvia Cravero Expert for WMF Heinz Ruther and his team from University of Cape Town – South Africa for providing fundamental documentation during the research activity.

INDEX 1.

HISTORICAL AND ARCHAEOLOGICAL INVESTIGATION TABLE 1. I

P.6 P.10

TYPOLOGIES OF ROCK-HEWN STRUCTURES

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2.1 Rock-hewn heritage 2.2 Type classification: definition, evolution and diversification 2.3 The original types: natural caves and rocks 2.4 Basic types: hewn cavities or carved rocks 2.5 Integration of base types : vertical cliffs, quarries and mines, caves with monoliths 2.6 Integration of basic types: cave dwellings on cliffs, trenched, court and monoliths 2.7 Further elaboration of original types: art, productive and hydraulic structures, cave architecture 2.8 Evolution of base-types: hypogean architecture 2.9 Complex types: rock-hewn cities TABLES 2. I-VIII

P.11 P.11 P.13 P.14

3. THE URBAN NETWORK AND MANAGEMENT OF THE ECOSYSTEM 3.1 The organisation of the site within its natural context 3.2 Spatial integration and economic intensification 3.3 Monumental transformation and construction of the urban ecosystem TABLES 3.I- VII 4.

ANALYSIS OF DECAY FACTORS 4.1 Analysis of the erosion factors TABLE 4I

5. STRUCTURAL ANALYSYS 5.1 Structural issues characterizing the rock hewn complex of Lalibela 5.2 Synthesis of structural vulnerability 5.3 Fractural patterns and static consistency in some relevant cases 5.3.1 Biet Medhane Alem 5.3.2 Biet Mariam 5.3.3 Biet Emmanuel 5.3.4 Abba Libanos 5.3.5 Biet Gabriel Rafael TABLES 5.I-VI 6.

PREVIOUS RESTORATIONS 6.1 Sandro Angeliniâ&#x20AC;&#x2122;s restoration work 6.2 Restoration interventions on individual churches 6.2.1 Biet Medhane Alem 6.2.2 Biet Emmanuel 6.2.3 Biet Mariam 6.2.4 Abba Libanos 6.2.5 Biet Gabriel Rafael

P.15 P.16 P.17 P.18 P.19 P.23

P.58 P.58 P.59 P.62 P.66 P.77 P.77 P. 85 P.86 P.86 P.87 P.89 P.89 P.91 P.91 P.92 P.93 P.97 P.105 P.105 P.106 P.107 P.108 P.109 P.109 P.110

6.3 Interventions after Angeliniâ&#x20AC;&#x2122;s restorations TABLE 6.I

P.110 P.113

LINES FOR AN ARTICULATED INTERVENTION OF RESTORATION 7.1 The Pilot Yard and waterproofing 7.2 Integrated operational strategy 7.3 Monument restoration strategy

P.118 P.119 P.120 P.122

TABLES INDEX Chap. 1 - HISTORICAL AND ARCHAEOLOGICAL INVESTIGATION

1.I Physical map of Ethiopia -The Lasta Region Chap. 2 - TYPOLOGIES OF ROCK-HEWN STRUCTURES 2.I Typologies of rock hewn structures 2.II Tab. C2.III Tab. D 2.IV Tab. E 2.V Tab F 2.VI Tab. G 2.VII Tab H 2.VIII Aerial View of Lalibela Chap. 3. THE URBAN NETWORK AND MANAGEMENT OF THE ECOSYSTEM 3.I Three-dimensional altimetry model 3.II Territorial typologies IIa Western Group IIb Northern Group IIc Eastern Group 3.III Hydrographical simulation of torrential rains 3.IV Geomorphology Map 3.V Urban Structure 3.VI The trenched city of Lalibela 3.VII The urban synthesis Chap. 4. ANALYSIS OF DECAY FACTORS 4.I Typologies of erosion factors Chap. 5. STRUCTURAL ANALYSIS 5.I Synthesis of the systemâ&#x20AC;&#x2122;s static interpretation 5.II Abba Libanos 5.III Biet Gabriel Rafael 5.IV Biet Medhane Alem 5.V Biet Mariam 5. VI Biet Emmanuel Chap. 6. PREVIOUS RESTORATIONS 6.I Realization of the shelters

WORLD MONUMENTS FUND CONSULTING AGREEMENT CONSERVATION ACTION PLAN FOR THE ROCK HEWN CHURCHES IN LALIBELA Team Leader Pietro Laureano July 2008 Final Report 1. HISTORICAL AND ARCHAEOLOGICAL INVESTIGATION From the historical and archaeological point of view, the site of Lalibela still presents various uncertainties. Most of the research is based on the sacred tradition according to which King Lalibela, who reigned from the end of the XII c. A.D. to 1220 A.D, built the churches. He was the most illustrious sovereign of the ZaguĂ¨ dynasty that established itself in Ethiopia in the areas of the Tigrai, Lasta, Angot, Amhara and in the North of Scioa between 1135 A.D. and 1270 A.D. Lalibela set his capital in Roha city which later took on the name of its sovereign who transformed it into the symbol and stronghold of his theocratic dynasty, image carved in the rock monuments of the Celestial Jerusalem, the sacred epicentre of the Ethiopian Christian Coptic Church. The city is set in a strategic position on the ridge of the Ethiopian upland, on the road that leads northward to Axum and to the Read Sea coast, in the heart of the Lasta mountain region, protected by peaks and deep gorges that channel the monsoon rains towards the tablelands and the river basins. Lalibela is situated at an altitude of 2463 m on the slope of the Abuna Yosef massif, whose highest peak in the East reaches 4.190 m. Set between two deep gorges seasonally watered by two river that belong to the Tekazze water system, a Nile tributary, Lalibela is a true fortress controlling the water sources, a vital resource for the region. It is precisely for the management o water that Lalibela was laid out on the basis of an extended territorial and urban scheme that also included the monuments. It is difficult to say to what extent Lalibela built the structures ex-novo or adapted pre-existing buildings. But certainly if we consider the general planning system, not only the eleven monuments traditionally held to be churches, a very complex and impressive territorial organization emerges. The urban system is set within a formidable network of ditches, trenches, channels and cisterns for water collection with an extraordinary spatial distribution that is probably the result of several interventions in time. Specific investigations and archaeological diggings would be necessary to establish the Who, Why and When, but they are not practicable at the moment. However it is possible to make a classification based on typology. The investigation will therefore be carried out through: a) The classification of the construction types of monument; b) The identification of significative elements in the organization and management of the environment c) The urban structure. a) the types of monument The definition of the architectural types and of the structural elements of the site make it possible, in order to enable its protection, to trace if not a proper chronological order at least a classification of different constructive moments. In fact the research, apart from the historical

and archaeological interest, is necessary for the comprehension of the degradation and for identifying a correct restoration action because it enables to find pathology families and indications for similar kind of intervention. The main feature of the monuments of Lalibela is that they are dug in tender tufa rock based on basalt strata. They constitute rock-hewn architecture and the Lalibela monuments in particular are defined monolithic. In reality, only a few of them are true monolithic structures that are separated from the main rock on all four sides and from the top. There are some true monolithic structures, some semi-monolithic ones and some rock-hewn cliff hypogeal and other types of dug architecture. The detailed classification and terminology of the various constructions is necessary for each restoration action because the structural conditions, the fracture pattern and the degradation and risk factors all present different situations depending on the different types of construction. In general the structural peculiarity of rock-hewn architecture as compared to built up architecture rests in the fact that the former is strictly connected with its mother stone. This causes advantages and disadvantages. As a cohesive system it has more chances of supporting and distributing the weights, also if shocks occur, but it also presents risk since it is subject to all hazards such as damp, water infiltrations, shifting and subsidence occurring in the rock system it is set in. The more monolithic rock hewn architecture is, or the freer it is from the mother stone, the less it is subject to the negative effects of the surrounding environment. Generally a true monolithic structure, deriving from the carving of a unique block, presents some pillars, arches, vaults that are all attached one another and firmly anchored to the ground and the ceiling. The structures, therefore, do not suffer from static engagement as do thrusting structures, and are less sensitive to shocks. However, when they are very large as in the case of Biet Emanuel and Biet Medhane Alem, they suffer more from the effects of seismic shock due to the oscillation of the elevated parts where the enormous load of the roof puts pressure on the structures detached from the mother stone on all four sides. Moreover, often the monolithic typology is structurally speaking only apparent. In fact the natural discontinuity and fractured surfaces interrupt the internal cohesion of the rock, making the monolithic structure similar to architectures working from a static engagement point of view- as thrusting structures. Hewn out cavities and rock shelters, not strictly monolithic, are less prone to seismic risk since they are anchored to the rock. However, they have specific pathologies due to the fact that they belong to the main slope with which they share the humidity cycle, the mechanical deformation and the possibility of disastrous collapse due to plane and landslide; a striking example of this is Abba Libanos. b) environmental management The identification of significant factors in environmental organization and management and the structure of the city plan are essential for the comprehension of the site and its safety. The constructive programme of the Lalibela site is not limited to the churches but it includes all the surrounding territory with its complexity of artefacts and with its linear structures for special organization to which the monuments are intimately connected. It is easy to realize that the position of the three complexes of the churches, called I and II group plus Biet Ghiorghis and that we prefer call Northern Group, Eastern Group and Western Group in reason of the geographical orientation, were chosen on account of their potential for the control of mountain floods. The three monumental groups are situated on protruding tufa-like

rock on gentle slopes, which then drop down sharply and along which floods flowed. These inclinations have been largely dug as part of a great urban design that is difficult to decipher on the ground. The conspicuous trenches are the perimetral ones of each group; they also are organized on slopes, courts, tunnels, run-offs and water collection points; thanks to the difference in altitude they collect, manage and drain the water. The organization was certainly a conscious choice of the medieval period that conferred harmony, scenic grandeur and representative energy to the entire system. We can say this not only because in adherence to a sacred tradition cities should be built according to the ideal model of a celestial design, but also by interpreting the structural elements of the system. For example by examining trenches, channels and underground tunnels, deriving from the two main monumental groups, set in a barycentric position in relation to the entire complex. Here starts the natural flow of the torrent that is called the Jordan River, a Tecazzè tributary. In this point, for rather mysterious reasons, since it is quite far from the monumental complex, an impressive monolithic cross was realized. It was at first forgotten and subsequently freed from the sediments, which had covered it, by Sandro Angelini during the first great works for the rediscovery and digging of the draining trenches, that he carried out for the WMF in 1967. It has an extremely important value because it marks the centre of the elaborate urban and environmental organization of the site that was realized in medieval times and highlighting the planning characteristics of the complex organization. This grand design is, undoubtedly, grafted on a longer period construction process. Lalibela, like all historical cities, although it has lived some intense moments of spatial organization, was not created in one single period and has its roots in the remotest Ethiopian history. c) The urban structure. It is not easy to assess the historical periods in which the site was built. In Ethiopia troglodyte dwellings and hypogean architecture are rooted in tradition and are widespread. From the VIII C. to the XV C. a. D. the phenomenon of rock dwellings with criptae, monasteries and hypogean churches, is common in the mountain ridge area from the Tigrai in the North to Addis Abeba in the South, passing through the central Lasta. In the Tigrai, in the area between the courses of the two tributaries of the Tecazzè, which has been called the Mesopotamia of Ethiopia, the name of the city of Ucrò derives from root “waccara” which means, “dig”. Important rock dwellings are found in Socota, between Axum and Lalibela and also at Yaha near Addis Abeba. The process has a strong religious connotation and in this respect it is similar to what happened in Syria, in the Thebaid, in Cappadocia and in the dwelling systems of the Gravine, which have as their best-known centre the Sassi of Matera in Southern Italy. In all these cases the medieval rock dwelling with a Christian and cenobitic connotation, does no other than referring to troglodite architectural themes and situations present in the area since prehistory. In Etiopia in pre-Christian times, during the Axumite era, which goes from the 1st b. C to the 7th c. a. C. the great religious and civil monuments consisted of architectures relying on masterly assembled large fashioned square stone blocks. This, however, does not exclude that a tradition in rock dwelling architecture existed. During the late Axumite era, when Christianity was already established, the construction of monolithic churches is attributed to King Caleb in the 6th c. a. C. According to religious chronology four hypogean churches existing a few km north west of Lalibela are attributed to this period, one of which, Bilbola Kirkos, should have been built by the same Caleb and the other three, Bilbola Ghiorgis, Arba Tensa and Tukurza Miriam, by his contemporary relations. 45Km north of Lalibela the magnificent complex of Imrheane Kristos is an example of the fusion of archaic traditions with the styles of the ancient built architecture. The church dating back to 1150 a. D. predates by a century the buildings of Lalibela. The architecture of the monument displays a perfect Axumite

style. It has a square shape with turrets on the corners. Sturdy pillars of red stone support it and the faรงades are made of rows of white plastered stones, alternated with horizontal beams of wood. The peculiarity of this splendid building is that it has been built inside a great cave. The monument recalls a recurrent phenomenon in rock hewn architecture: the sacred role of caves, very ancient cult sites, going back to prehistory and connected with the vital role of water and of Mother Earth, in all periods that followed. Therefore Lalibela is not unique, suddenly and mysteriously realized, but it is the product of a long, a very long, tradition. The Lalibela kings, replacing the Axummite Dynasty and asserting their dynastic and religious power, adopted cultural and building habits connected with cave dwellings, as it was customary in the most inhospitable mountain region of the country, inherited from the remotest past. In fact the Lalibela Dynasty is the expression of the Agau people inhabiting the North East of the Lasta, where in the district of Bughena had their capital city Aadefa, on the slopes of Mount Asceten. The Agau utilized caves like in ancient times and were in the habit of digging great artificial caves. Furthermore, the character of their habitat made them masterly organizers of drainage and water gathering systems. Still to this day on the higher plateaus of Abuna Josef, villages still inhabited and lively are bordered by great semi circular trenches whose role is to drain and keep the land dry during the rainy season, and also work as a water reservoir in the dry season. These structures are very similar to trenched neolithic villages of Southern Italy situated in areas of troglodyte and rock dwelling traditions. At Lalibela the continuity with such building practices is evident. Some channeling works and digs in rocky tables clearly show to be older than earlier traces of huts whose bases are deeply entrenched in the tufa. These huts floors have been in their turn cut by medieval tombs, the latest work in the process. A typological classification will enable to clarify this long process of a local traditions going back to prehistory, reconciling Axummite Classicism with influxes from the Coptic Egyptian Church and from the multi ethnic cosmopolitan melting pot of the medieval Church, sensitive to Byzantine, Arab and Indian influxes, which have enabled the great vision of King Lalibela to be carved in the stone.

TAB. 1.I Physical Map of Ethiopia – The Lasta Region

LALIBELA

2. TYPOLOGIES OF ROCK-HEWN STRUCTURES 2.1 Rock-hewn heritage The structures of Lalibela fall under the category of rock-hewn heritage. This includes works of art, architectures, dwellings, hydraulic and productive structures, found all over the world and existing from the remotest times. Such craft may consist of the mere use of cliffs and caves as shelters, wall art, and increasingly more complex caves up to the construction of habitat systems high up on precipitous rocky ridges and ravines, to culminate into underground cities built inside the bedrock of a plateau on several levels. A close association with the natural environment characterizes the world of rock art, which by its very nature is based upon an intimate structural relationship with the living rock. When rock-hewn works are found underground they are called hypogean. Hypogean structures are therefore an essential component, albeit not the only one, in matters of rock-hewn artefacts. There are natural or man-made underground structures, not all such rock-hewn works, however, are found underground. Trenches, walkways, quarries and courts may be rock-hewn and open to the sky. Monolithic structures are three-dimensional blocks, cut on all sides but remaining anchored to the bedrock on the bottom and open to the sky; at the same time they may also be called hypogean since the interior of the monolith is hollow. The motivations behind rock-hewn and hypogean architecture are strongly connected with environmental integration and sustainability. Man digs in to obtain, for example, a constant temperature in summer and winter, or in order to find a water supply, to cut the cost of building materials, to create durable structures, to create shelters or to conceal a building or, again, to build in harmony with the surrounding environment and finally for symbolic or spiritual reasons. 2.2. Type classification: definition, evolution and diversification Classification helps to divide such crafts according to type categories, by identifying a matrix (abacus) of types of rock-hewn structures, within which to place these according to classes (Tab. A), all this leaves aside the problem of historical period, architectural style or canon, as treated by art historians. A typological approach provides a clear scientific terminology conducive to an exam of architectural styles, and also possessing an operational quality. In fact, to different types correspond specific structural dynamics, or pathologies, and thus calls for intervention. We must however not mix up type with actual monument. The type is an ideal model to which we refer, in abstract, a multitude of objects displaying common characteristics. The real monument, consists of an original expression, it is the result of continual transformations, superimpositions and also changes of its fundamental functions, through a particular history, which needs retracing. Thus typological evolution must not be confused with historical chronology. The typological process, according to which, from the original patterns existing in nature, basic types emerge, which in time evolves in more and more complex types, diversifying according to environmental and cultural factors, constitutes an ideal model. This does not necessarily follow in every specific case. Types emerge and change, they evolve and diversify or remain anchored to basic patterns according to place, culture and historical period. Original types may perpetuate themselves unchanged, on the other hand basic archaic types may have been built in recent times, and even co-exist with ancient complex types. Typological classification does not concern, therefore, environmental or historical determinism. There is no substitute for an architectural knowledge of the specific monument, acquired through survey, historical research, and analyses of its transformations through time, structural analyses, definition of artistic and architectural canons.

Classification by means of the matrix of types enables the identification of the monument and places it into a wide interpretative framework generating extensive comparative parameters concerning its origins, connections, and evolutions at a local or international level. In fact, a creation is never isolated, neither physically nor culturally. From the physical point of view the architecture will be connected to the natural matrix. From the cultural view point the work is the outcome of a network of relations, connections, analogies, which has continuously undergone contaminations and transformations. The object is part of an environmental context and of a network of cultural connections that from the local extend to wider worlds. Both factors, the environmental context and the cultural universe, cause its genesis, its technical and social function, its role and meaning within the entire ecosystem. The general picture of rock hewn typologies is synthesized in Tab A (Typologies of rock art types). The plate provides a general definition of world rock hewn crafts types. It shows horizontal lines which illustrate the evolution of types in rock hewn architecture, divided into nine categories, and by vertical columns within which types are divided according to natural morphology, this is to say the nature of the matrix. 2.2.1 Evolution of types On the horizontal lines types are organized into categories (from A to K) according to a progression going from simple rock shelters to complex troglodyte underground cities. The first and second categories (A) Use of rocks, crevices, and natural caves, and (B) Structures inside caves and hollows constitute the original types used as they come in their natural state. From these derive basic types (C) Hewn out cavities or carved rocks that fully represent hypogean and rock cut activity. The integration of basic types defines category (D) Hewn out cavities or carved rocks in various matrices, as resulting from a combination of various articulated types in a variety of morphological situations. With the artistic, architectural and productive evolution of rock-hewn crafts, an elaboration of original types takes place. These are shown in category (E) Works of art, hydraulic and productive structures, in cave architectures. Through the evolution of basic types a true rock hewn hypogean architecture emerges, and this is dived into (F) Hypogean architecture by subtraction and modelling; (G) Hypogean architecture with carved or built up faĂ§ades; (H) Three dimensional hypogean architecture. The subsequent level of integration and complexity consists of (K) Complex types, which are true rock cities. 2.2.2 Diversity of types In the vertical columns of the graph, each category is identified according to its position within the natural morphology hewn into vertical cliffs (Column I), on slopes or plains (Columns from III â&#x20AC;&#x201C; to V). Cliffs may be natural such as the natural falaise or wall of a canyon or man made by dinging. In both cases, in cliff types, beginning from the cliff face, the cavity extends horizontally or quasi-horizontally inside the bedrock. Structures on slopes or plains are divided into pit, lineal, court and monolithic types. In these cases cavities extend vertically top to bottom. We call a pit a surface cavity of smaller size. Lineal are those that extend horizontally in a straight line. Cavities and passages may be on the surface, open to the sky, or underground. In cases in which the cavity is very wide, we call it a court, which is open to the sky and has its floor and walls hewn into the rock. In it may stand spared blocks of bedrock standing like monoliths. 2.2.3 Pseudo-hypogean types A last column of the graph (VI) is separate from the others since it includes man-made structures that we may describe as pseudo-hypogea. These buildings reproduce, with their structure, the

characteristics, the mass, the morphology and functionality of actual hypogea. Among such pseudo-hypogea we find archaic megalithic constructions such as the Sardinian nuraghi and the Maltese temples as well as some modern architectures. A fundamental component of pseudohypogea are megalithic blocks. Rows of rocks and megalithic constructions made of locally quarried blocks, which may be described as pseudo-rock hewn structures. At Lalibela we may put into this category megalithic walls (a sacco = wide walls of dressed stones on either side and filled in with rubble) of which we observe the vestiges near the complex of Biet Gabriel Raffael in the Eastern Group and along the road of access to the Tomb of Adam in the Northern Group.

2.3 The original types: natural caves and rocks. The raw materials of rock-hewn architecture are rocks and cavities. These exist in nature and are utilized as they come. The occupation and use of these by man turns them into cultural environments that we describe as original types of the rock system. In the lines A and B of the graph of rock art categories, we observe the use of caves, crevices or cavities as they are in nature: In section A (use of caves, crevices, or natural cavities) we find those utilized with no alteration, in section B (structures in caves or natural hollows) we find shelters to which other elements are added, generally wooden, or to which small functional alterations are made for their use. The typology of structures relative to cliffs concerns rock shelters (A1) prehistoric caves and dwellings, other shelters, cult places in caves overlooking canyons (B1) including those organized with steps and stone walls, like the villages of the Anasazis of Mesa Verde in Colorado. Natural cavities such as potholes, and natural gutting holes (A2) may be used both as shelters and for collecting water (B2). Natural lineal structures such as erosion ditches (A3) or Karstic rivers which are used both as walkways and as shelters (B3). The geological terrains of the doline, or the polje of the Carso, the puli of Apulia, the chultun of Yucatan, constitute the first natural court (A4). Around the perimeter of these natural basins and potholes, Karstic cavities may occur, in which case the court dwelling type with radial galleries emerges (B4). Natural monolithic structures (A6) are any rocks or boulders utilized as they occur. The latter often acquire a sacred or symbolic meaning on account of their shape that may be seen as anatomical or anthropomorphic. These may be small stones and rocks, or may be of considerable size thus becoming distinctive landmarks such as the great isolated rocky formations of Cappadocia called â&#x20AC;&#x153;Fairy Chimneysâ&#x20AC;? (A5). In natural caves, pure and thus holy water, drips from stalagmites. Thus emerges a process of sanctification of monoliths, of stalactites, stalagmites, upright stones and rocks, widespread around the world. Near Lalibela in the church of Nacuto Laab (B5) we may observe the process. The church is hewn out of a natural cave; before its transformation, water was collected from its stalactites with stone basins placed under them. The greater part of cases illustrating original typologies may be observed in the territory around Lalibela but not on the site itself. At Lalibela types have, in fact, undergone a process of transformation consisting of the evolution of original basic types culminating in the existing complex urban typology. The process may be observed in the case of the ditches where original lineal natural structures of rivulets and furrows caused by erosion, give rise to the deep trenches evolving into the integrated type of the trenched village and on to the colossal structure of great trenches of which the rock-hewn city consists.

2.4 Basic types: hewn cavities or carved rocks.

The beginning of hewing and modelling works marks the transition from a phase of mere possession of the natural site, as it is in nature, to its transformation. Here are the basic types of rock-hewn craft as classified in scheme C that include hewn cavities and carved rocks. According to natural morphology, these types are thus divided: cliff type, pit type, lineal type, court type and monolithic. 2.4.1 Cliff Cliff hypogea (C1) utilize the cliff face of falaises and canyons as they exist in nature, or may be hewn out of artificial walls especially obtained along rocky slopes. Horizontal excavation spans from the mere widening of a natural cave or from its imitation, to more elaborate organic forms such as lobes, cells, tunnels (cunicula) or geometric forms like chambers, systems of chambers. At Lalibela, hermit monks used small caves hewn into the walls of trenches, even in recent times. 2.4.2 Pit Along slopes and flat areas, vertical hewing creates wells and chambers (C2). This is the type utilized for tombs, shelters and shrines or as cisterns for water and as baths. The sacred spring, near Biet Ghiorghis, is a case in point at Lalibela. 2.4.3 Lineal When the work stretches lengthwise we have lineal rock structures (C3). These may occur on the surface or underground (lineal hypogean structures) The surface ones include trenches, ditches, drainage galleries and collecting wells. A case in point is the system of great trenches at Lalibela. These have, in time, undergone several phases of restoration and evolution; this before the Medieval excavations, monumental reshaping. The basic trench type is shallow, and sinuous is its development and smooth like a natural stream which constituted the model for such structures. The ditch works as a drain as a canal, and as a drinking trough. In this case their shape is a semi-elliptical trench that above it captures the waters conveying them to the sides of their natural fall. Straight trenches are instead dug along the lines of maximum tilt and serve for drainage and channelling. Special transverse channels cut across the main slope are called tagliate (cuts), from the Italian name given to structures created by the Etruscans, existing in Central Italy during the 1st millennium BC and also found throughout prehistoric rock-hewn works from Albania to the Murge of Matera and Apulia and in Malta. These great trenches in the rock break the flow of rainwater running down a slope, conveying it into collecting wells, cisterns and also providing vertical walls where rooms may be hewn out. To these, the inhabitants may associate partly hewn out sunken huts on the slope free from flooding water, or inside the trenches. The tagliata type of structure is recognisable in the ditches of Lalibela, placed lower than the Northern Group, where two trenches in the rock capture the waters flowing from the rocky slope and probably constituted an overflow for the basin below, still visible across the road. On the above slope there are traces of cuts and works ascribable to pre Christian huts since superimposed with medieval tombs. Lineal underground structures are galleries, tunnels, mazes and also complex water works such as drainage galleries. At Lalibela exists a variety of types of underground tunnels, passages, galleries 2.4.4 Courts The excavation on the rocky plateau of elliptical or square pits creates a rock-hewn court (C4) an artificial emulation of the original doline type. The court may have an organic circular perimeter as in the case of Matmata in Tunisia and may consist of a simple type pit court. Several semi

circular rooms may open out onto the court, the whole forming a lobular structure. Courts may join up in a cellular system or create a geometric and are in this case orthogonal courts. Great systems of square plan courts hewn into the loess exist in China in the province of Xinjiang. At Lalibela courts are squared, but take precise geometric forms only during the complexity phase of architectural elaboration of the Medieval period. In the more archaic basic types these have elongated shapes or pseudo-rectangular, still visible in the court still in use as a rear faรงade of the present complex of Biet Gabriel Rafael. 2.4.5 Monoliths The hewing of pits in bedrocks is carried out leaving some blocks of original rock standing, which become monoliths (C5) When blocks are totally removed from the living rock we have free standing monoliths, such as are menhirs, stelae and obelisks. When instead they remain attached to the bedrock at the bottom they are monolithic pillars. We find such structures at Lalibela: the monolithic cross marking the start of the Jordan, and the monumental South Gate with monolithic battlements by the great trench of the Eastern Group.

2.5 Integration of base types: integration cliff-plain, quarries and mines, caves with monoliths Basic types take shape and merge generating more articulated systems. Trench systems in the plain may stretch out with tunnels and reach openings overlooking valleys or man made cliffs thus creating underground connections between the plain with the canyon. Solutions, articulations and complexities of types are found both in caves and mines. These may take the character of the above described types: cliff, pit, open sky, underground, tunnels (C) and integrate with systems of water collecting, dwelling complexes, often all using cavities resulting from excavation. Many techniques of such rock-hewn craft derive from accumulated experience. The court and vertical pit-well type with radial tunnels is found, for example, in the Neolithic flint mines of Grimes Graves in Great Britain. The vertical pit enables one to reach the flint nodules that lay in the horizontal strata of the chalk. Quarrying flints from the strata demands the digging of radial tunnels. The type realized belongs to the typology of the rock-hewn hypogean court habitat. Monoliths too bear a relationship with the experience of quarrying. In the formation of an open sky quarry the bedrock is cut vertically into a rocky plateau. Some parts of the cave, often the central part where the hewing process starts and where materials and equipment are kept, remain unexcavated and can be used as access ramp. These areas of the caves remain often isolated in the middle of the quarry and form the premises for future monoliths that will stand within the court. At Petra in Jordan and in Etruscan Tuscania, when a whole rocky plateau was quarried, monoliths remain standing as indicators of the height of the original plateau. At Lalibela an open quarry of megalithic blocks is recognizable on the West side of the Biet Gabriel complex. The excavated structure, with a triangular plan forms a water collecting system on the slope that conveys the water to the cisterns of the ditch. This structure bears the marks left by the quarrying of rectangular blocks that were removed and taken away. Probably such blocks are still there on the site of the complex. 2.6 Integration of basic types: cave dwellings on cliffs, trenched, court and monoliths

2.6.1 Cliff On the hewn out matrix dwellings and settlements grow. When the matrix is a perpendicular cliff we will find troglodyte cliff dwellings (C). The most famous among these are the cliff dwellings of the Dogons in the falaise of Bandjagara, in Mali. At Lalibela, structures of this type are found along the northern edge of the great trench of the Eastern Group. The structures exploit the wall of the trench, thus the village constitutes a troglodyte cliff dwelling on a man-made cliff. 2.6.2 Trench Upon tilted levels villages are generally found in relationship with dug up trenches. During the Neolithic, since the 6th millennium BC, we find settlements enclosed within semi elliptical ditches and trenches. To this type belong the trenched villages of the Daunia and the Murge, in Apulia and Basilicata, in Italy, the village of Koln Lindenthal, in Rhineland (Germany) and of Banpo in China. Ditches have the function of collecting and conveying water and discharges, thus fulfilling a number of needs. These settlements consisted of circular or elliptical huts, which have left their clear marks in the bedrock. Trenches collected and diverted rainwater, thus keeping the settlement area dry and also marking its symbolic limits, they defended the settlement providing, at the same time, good drainage. This practice is still found in the villages of the Ethiopian plateau, and it is likely that the ditches of Lalibela had in an archaic phase, the same function. The Eastern Group in particular, presents a structure characterized by elliptical ditches. From the different ways in which the rock is hewn, and from the different types of accesses to underground tunnels, we can clearly detect a number of chronological phases corresponding to as many different levels. The first ditches were shallow and narrow, therefore similar to those still in use in local villages. To phase two belong traces of rock settlements with huts present on the plateau south of the Northern Group, in the court of Biet Gabriel Rafael and along the glacis of the ditch by the entrance to the Eastern Group. The plans of the huts, hewn out of the bedrock present a double circle, or circles enclosed within a square drainage system. We clearly observe postholes, water holes and troughs used for corn grinding. South of the Northern Group we can see how these works pre-date a medieval rock cemetery that cuts through them. The medieval phase of the excavations concerns Lalibela, the capital city where ditches have been deepened widened and straightened up. Such intervention agrees with the addition of orthogonal courts and of the monumental monolithic churches of Medieval Lalibela, which needed deeper canals for its drainage system. 2.6.3 Court On the level bedrock, villages appear based on rock-hewn courts and water collecting pits. These are the already mentioned complexes of MatmatĂ in Tunisia and in Chinese Xinjiang, where rock-hewn courts are joined by means of underground tunnels, thus forming wider settlement units. The rock-hewn court is utilized as impluvium for water collecting and as workplace for the preparation of foods. Its corners, endowed with alternate phases of sunshine and shade, offer ideal positions for drying or protections foodstuffs. This becomes a natural system of protection and temperature regulation, enjoying cool draughts from the vents of underground tunnels. The court is also a centre for social intercourse and communal practices. In Italy, in the Sassi di Matera (Rocks of Matera), the system of rock hewn courts, has generated the anthropological category of neighbourhood, the meeting place, the place for exchange and social intercourse, within the kinship system of the extended family, here kept united by the communal court. At Lalibela archaic rock-hewn courts still working in this way may be seen in the court behind the complex of Biet Gabriel Rafael in the Eastern Group and in the court on the north side of Biet Mariam of the Northern Group. In these courts people still dry foods, grind corn and often

practice fundamental rituals of a religious, spiritual or social nature. In the rear court of Biet Gabriel Rafael and on the glacis of the higher ditches we detect traces of archaic hut settlements. 2.7 Further elaboration of original types: art, productive and hydraulic structures, cave architecture. To rocks, cliffs and caves the first forms of art are also associated. Prehistoric stone artefacts are also manufactured with an aesthetic and symbolic intent. The universally celebrated rock art of Prehistory is found on the back walls of rock shelters and in caves. The original sites of rock crafts, are rocks, natural caves and caverns, the places where the craft was created and where it evolved. This evolution continues in artificial structures to this day, but at the beginning the cave t is natural, it is not affected by any trasformation: it receives just the object.. In artificial caves where walls are accurately smoothed down or plastered in order to paint murals, architectural and productive or hydraulic structures may be inserted. 2.7.1 Cliff dwellings Inside cliff dwellings we may find frescoes, sculptures, arches, other architectures and productive structures such as mills, cellars, water reservoirs, wall cisterns, fountains. A very rich array of such artefacts, rock-hewn monuments and hydraulic works are found at Petra in Jordan, where hypogea are hewn out of vertical cliffs. Open-air structures such as steps, fortifications, water canals, monumental fountains are directly hewn in the rock. A particular case is the building of complete architectures, from foundations to roof inside caves, as if they were built in the open. At Lalibela, the site of Yemerhane Christos is the example of universal excellence of this type of in-cave architecture. The church is built in its splendid Axummite style as if it were a normally built up architecture separate from the rock surface, but built as a symbol and seal of the spiritual and cultural bond with the mother rock and local tradition. The church is entirely built inside a natural cave. 2.7.2 On plain On the level bedrock floor, architectures are obtained by digging vertical pits, lineal trenches or courts. Tumuli, dolmens and other burials made of stone blocks belong to the first category. Most important are water management systems such as wells, cisterns, snow wells, aqueducts water catchment systems, which may have underground and open air parts. These may become monumental complexes with a sacred connotation. At Lalibela the Spring of Biet Ghiorghis is a case in point of a sacred spring in a bedrock-hewn ditch. The quarry west of Biet Gabriel is a catchment for the water running along the slope, filling the splendid cisterns placed on either side of the ditch below. The system of the two trenches (tagliate = cuts) below the Northern Group was probably connected with the basin down below, before the interment of the system and the construction of the new road. The basin itself is connected, by means of a ditch, to the great trench that reaches the complex of Biet Ghiorghis. Imposing water distribution systems exist in the upper corner of the ditches in the Northern Group. 2.7.3 Court type With the term hypogean court structures, we may identify all cliff â&#x20AC;&#x153;megaronsâ&#x20AC;?, quadrangular dwellings fronted by an impluvium, distributed during the Bronze Age from Mycenae to the rock sites of Pantalica in Sicily and Gravina in Apulia. At Lalibela, there are numerous water tanks and reservoirs connected with courts where there are numerous tanks and bathing pools provided with monumental entrances and stairs. An interesting structure is the rock hewn access ward of a rock dwelling with double chamber and connected, by means of a tunnel, to the great trench on the east side of the Eastern Group. Inside the courts there are also areas devoted to structures

for production activities, such as mills, tanks for the treatment of wool, storage pits and storage rooms. 2.7.4 Monoliths Monolithic structures are carved into geometric volumes or into zoomorphic form like the Serpent monolith of Petra, or containing carvings and painting inside. Sometimes the craftsman carves out a whole cliff in architectural form, as it is the case of Kubbeli Kilisi in the Soğnali Valley in Cappadocia, which is a rare example of a pinnacle modelled into the shape of a church dome. At Lalibela, we may include among hewn-out monoliths Adam’s Tomb that recalls the parallelepiped of Petra. Grand rock hewn wall art is present in the monolithic churches of Lalibela with a profusion of frescoes, relieves, windows and architectural mouldings carved and painted, of which Biet Mariam and Biet Golgotha are excellent examples. 2.8 Evolution of base-types: hypogean architecture A fundamental typological evolution of the base-type occurs when from a basic excavation reproducing the original types within which other structures are inserted, we pass on to an action that while excavating it creates a complete architecture. This is a true hypogeal architecture. It is an action that at one times it involves hewing the rock and shaping and structuring an architectural project. Hypogean architecture presupposes a blueprint: its aims are not to create a mere cavity, but to create a work according to a functional design. The architectural form may be achieved by subtraction and modelling, by cutting an interior and hewing a monumental façade or by creating a three dimensional architecture. Each of these categories varies according to the morphology of the site, to whether this is a cliff or a rocky plateau. 2.8.1 By subtraction and modelling On vertical cliff faces, by hewing, or subtracting rock and simultaneously modelling, hypogean rock architectures are obtained. The exterior of the cliff face may remain unaltered, but the interior is hewn and carved in such a way as to realize a project up to the finest architectural details. From basic tomb structures reproducing, as in Etruscan burial tumuli, the ceilings evolve from the imitation of mere roofing structures to replicas of the ceilings of a house, or temples and churches by hewing architraves, columns, plinths and arches. At Lalibela an example of this type is provided by the Cave Church of Biet Danaghel of the Northern Group. In the same way, architectures are created in tilted or level rocky plateaus. Accesses may be from pits o ramps and the structure is no longer a cave. From basic trenches or chambers we move on to underground complexes on several levels and to imposing hypostyle halls supported by massive pillars, such as in the Ramesseum, the funeral temple of Ramesses II, at Thebes in Egypt, dating back to the 19th Dynasty, 1301-1236. At Lalibela, in the complex of Biet Mercurios, it is possible to detect a hypostyle hypogean structure, probably belonging to an archaic phase, earlier than its transformation into a church. The pits of Alexandria in Egypt belong to this type; they are based upon lineal or labyrinth systems accessible from a spectacular staircase in a well. With the court type obtained by subtraction and modelling elaborate open sky rock architectures may be obtained with accesses to hypogea, or underground works. In the hewing of courts parts of the rock are spared in order to create ramps, plinths, platforms or, as in Petra, cubic monoliths. At Lalibela the court at the rear of Biet Gabriel belongs to this type. 2.8.2 With built up or carved façade

Carved or built up cliff architectures with elaborate faรงades fall into this category. Cliff-face hypogea show an extraordinary number of varieties of this type: the complexes of Abu Simbel in Egypt, with their monumental statues on their faรงades or the tombs of the Persian kings of the 5th C. BC in Iran. The Buddhas which stand by the caves of Maijisan in China, the sculptured faรงades with architectural motives of the monumental tombs o Lycia in Turkey or Petra in Jordan, and Biet Maskal at Lalibela. On level, rocky plateau fall into this category underground hypogea with monumental entrance on the surface accessible through ramps or wells. In Cappadocia rock-hewn houses or churches conceal the accesses to the underground city. The same happens in the underground structures of the Roman hypogean city of Bulla Regia in Tunisia, accessible from aboveground architectures or from the patios of ancient houses. At Lalibela the construction of the monumental faรงade in court systems gives rise to semi-monolithic typologies. These are complexes and monuments with carved walls on three sides and roofs of the same bedrock as in Biet Gabriel, Abba Libanos and Golgotha Micael. 2.8.3 Three-dimensional When the work is completely hewn out of the bedrock all around on four sides and the top, we speak of three dimensional architecture. We call the site a court since the monument is obtained by hewing the rock all around it thus forming a court, and monolithic because the monument stands free in the middle of it and it is also hypogean because the interior of the monolith is hollow. The peculiarity of rock hewn tree-dimensional architecture is that works of this kind reproduce with the highest precision the structures of built-up architecture. It is therefore the product of an artistic convergence which has fully assimilated the structural and decorative canons and principles of both built up and rock-hewn hypogean architecture. One of the most significant examples of this type is the Ellora complex in India, made between the 5th and the 13th C. AD, along with the monolithic temple of Kailasha, 82 metres long, 42 metres wide and 32 metres high, dating to the 8th C. AD. This typology is the one that makes world famous the complexes of Lalibela. Biet Emmanuel, Biet Medhane Alem, Biet Ghiorghis, Biet Mariam is totally monolithic rock hewn churches the result of an architectural and spiritual project, a synthesis and a convergence of troglodyte practices and celestial craving. Albeit hypogean, these churches are something completely different from a cave, they are hewn out of the rock but ideally removed from it. They are proper architectures but at the same time they are intimately rooted to mother Earth. 2.9 Complex types: rock-hewn cities Integration, evolution and elaboration originate complex systems. These are the result of growing social and economic interaction, and thus the state of settlement or village is superseded by what is a true city. These boast a relatively large size and extend over a diverse natural environment, including the plateau, the falaises and the ledges of lower slopes. Rock dwelling sites surprise us for their ability to generate a system that is perfectly integrated with and adapted to its environment. However, this situation is not, in fact, accomplished as it appears to us. Complexity is the result of a process of accumulation of knowledge and of sedimentation of techniques over a long period. It is the result of the elaborate articulation of appropriate solutions, tested according to a trial-and-error method by which small scale communities with low energy consumption progressively respond to adversity and change. In this way a system is generated which is capable of facing climatic change, environmental emergencies, and community needs. The process of elaboration and evolution does not proceeds steadily and continuously or solely in

response to endogenous dynamics. Due to impulses caused by social and spiritual energies, to the ability to cause innovation, to the influence and guidance of local or foreign personalities, to events and changes at a local or general level, moments of intensity and leaps forward occur. To the formation of a complex type contribute foreign influences, contacts, contaminations, cultural assimilations, migration flows and also the effects of political domination. What determines an advance is a wider context of relations, caused by the constitution of political administrative and religious entities on a regional or national scale, or the inclusion within a system of commercial roads and exchanges. Change affects at one time dimension and quality; an essential role is played here by ideals and spirituality. The transition to complexity is always powered by a leading charge: the will to assert a great vision and to represent it in the city of stone, by imprinting it forever in its own matrix. Each rock hewn city carries the hallmarks of a specific period, which becomes the theme of the city itself, representing the spirit of the place, often overshadowing its long evolutionary history. In this respect, Petra is the hub of Hellenistic caravan trade; Matera the point of reference of the transfer from east to west of post-classical and medieval monasticism; Lalibela is the kingdomcity of a new dynasty. New and multiple functions, from residential to productive, to political and religious management, all have reflections upon the urban network which presents a multiple hierarchy of structures. Sometimes the general aspect remains that of a rock hewn and hypogean conurbation, that of a troglodytic city. In other cases grand monumental structures brand with their character the entire site, often built up architectures conceal its hypogean matrix. This however remains the space-matrix of urban evolution; ties with the environment remains always strong, so much so as to become an element of weakness of such sites which need, for their upkeep, a great deal of workforce and social cohesion. Many centres have collapsed since ancient times leaving only archaeological relics, others have not been able to survive a confrontation with modernity and have experienced degradation and desertion. In other situations the acknowledgement of monumental and cultural values have set off a process of conservation and promotion, albeit not always with a full awareness of the complex variety of the meanings and values which such sites carry with them. 2.9.1 Classification according to matrix Generally speaking we may classify rock urban complexes into the following types: cliff, underground, court and terraced steps, trenched courts. This classification bears in mind the environmental typology of the site, which defines the distinctive character of the city without however imposing clear-cut distinctions between phenomena that share strong common traits. This classification underlines the dominant traits, the idea and the force behind the cityâ&#x20AC;&#x2122;s character. This is identified in relation with the environmental system within which the settlement was created. Such matrix/space has often water and agriculture at its base, two elements upon which the city grew up through time. Techniques of environmental management and organization of resources in cycles of use and reuse, form a whole with the physical architectural, urban and social structures. The harmony with nature, landscape and environment is not only obtained by working the rock, but it affects every realization, structure, function, and it also reflects upon community practices, productive, material and immaterial: the city is a cultural ecosystem. 2.9.2 Cliff Cliff types are all those which have predominantly developed on cliff faces, in canyons of falaises. Here we find urban sites on several levels, with hypogean rooms hewn in the cliff. The general picture is that of a great cliff faĂ§ade dotted with widows and openings. To this category belong the Dogon settlements at Bandjagara in Mali and the Anasazi sites on the Mesa Verde in the

United States. In these cases built up structures are set against the cliff face which is also hewn out with troglodyte rooms. Most celebrated archaeological sites of this kind are Pantalica in Sicily, dating back to the 13th C. BC, many Etruscan settlements, and the site of Petra in Jordan. Medieval sites are the complex of Vordzia in Georgia, UĂ§hisar and Zelve in Cappadocia. Sometimes in temporary evolution ridge or plateau settlements prevail and these develop into rock-top complexes. At times expansion occurs in the bottom of a canyon such as in Petra where streets and squares develop between rock-hewn monumental structures all around, which create an impressive architectural scenery. 2.9.3 Underground In the plains, underground cities sometimes develop, consisting of elaborate urban complex. In Northern China, in the Shensi province, systems of orthogonal courts are dug into soft loess. Of the same type, but a lay out based on cells and lobules, are the sites dug out into the clays of MatmatĂ in Tunisia. The most extraordinary example of an underground city built on several horizontal levels, one below the other, is that of the Cappadocian centres of Derinkuyu and Kayamikili. Twelve km apart they are hewn out of the tender volcanic tufa, they present seven underground levels of labyrinths made of rooms connected by means of deep vertical wells. Underground cities of this kind, but probably found in Armenia, are also described by Xenophon in the Anabasis in 400 BC. 2.9.4 Courts and terraces The integration of the plateau with the gentle gradients of a canyon created rock cities based on courts and wide terraced steps. On levelled ground the court develops whereas the slope is organized in a series of terraces that descend gradually towards the bottom of the canyon. The most eminent example is seen in the Sassi di Matera that extends on 12 hectares on the two great bends of the Gravina canyon bed in Southern Italy. Courts and hypogea of the flat plateau connect with lower underground chambers giving onto the ledges of the cliff wall which gradually descend the slope until the soft tufa of lime/sandstone encounters a harder limestone bedrock, much harder to carve. There are up to ten levels of underground chambers, provided with hundreds of bell shaped cisterns connected between them by tunnels which convey rainwater from the plateau to the slope, and also provided with decantation and filtering tanks. Upon the network of channels and drain-holes connected to the cisterns, alleyways and courts have developed according to gravity lines. The roofs of hypogean dwellings below are the streets of those below. Caves are organized in semi-circles on terraces that work as threshing areas and gardens. With the blocks hewn out of the cliff built up barrel vaulted buildings protrude out onto the threshing areas: Generally speaking are the caves lateral to the threshing area which are built up to come out to the edge, forming a covered patio with their barrel vaults. Here we see the birth of the neighbourhood system, which creates the social space of the rock-hewn city. 2.9.5 Trenched courts An evolution of the Neolithic trenched camp is represented by urban complexes with an elaborate remodelling of natural morphology by means of great trenches. Ditches and canals have determined the success of great civilizations based on a wise management of water resources causing economic, social and monumental results. The splendid civilization of Angkor owes its prosperity to the excavation of colossal canals and ditches which in North East Cambodia surround with concentric rings human settlements constituting a tradition started in prehistory. These works of true landscape modelling are generally explained as systems for drainage and irrigation, but this interpretation is unsatisfactory. Even the defence theory is unsatisfactory given the easy to cross shallowness of the canals. Only the explanation which attributes a multiple role to the canals - as water reservoirs for the dry season, as

protection from floods during the rainy season, as devices for the drainage or conveyance of fertilizers and even symbols of community identity- seems capable of explaining the success of such structures. This is also the explanation for the ditches of Lalibela, which originate from ancient widespread local practices, developing and changing in time. At Lalibela the practice of digging ditches accompanies that of digging out tunnels, sunken courts and imposing hewn out architectures. In the urban network is clearly recognisable the typological leap represented by the appearance of structures such as Biet Emmanuel, Biet Medhane Alem, Biet Mariam and Biet Ghiorghis. These are hypogean three-dimensional architectures which correspond to an ideal blueprint and which confer a new physiognomy to the site. Such structures fall into the local typological evolution in harmony with the limits and the demands of the local environment. They clearly adhere, however, to new canons and languages. A fundamental role is played by the transition to an urban dimension and to the demands for monumentality within the Church. Churches show greater dimensions and precise geometrical designs; they are also east west oriented according to liturgical canons. They also demanded a transformation in the systems of access to courts; these must now be regular and deeper in order to enable the realization of taller monolithic structures. Lowering the level of the court where the church stands means deepening all accesses and also the drainage system. A typological analysis of the Eastern Group clearly shows that the creation of Biet Emmanuel occurred at a later stage in the development of the city. The court and the monolith of this church possess geometry and observe an autonomous orientation as compared to earlier structures. The structure clearly cuts through original tunnels whose level may be observed in the existing access to Biet Emmanuel that from the South East corner of the court leads to the ditch. The level of the passage rests half way up the ditch and it must indicate the original depth of the latter. When the court was deepened for the construction of Biet Emmanuel workers have at the same time lowered the level of the ditches, thereby reorganizing the whole system. The great medieval urban synthesis is the result of local evolutions of types, but it couldnâ&#x20AC;&#x2122;t be carried out were it not for a will and an idea vision. Local experience, fortified by further acquirements of knowledge, realize the monumental representation and celebration in an accurate management of environmental resources, carrying out a consistent harmonious design, the result of a precise plan. As local tradition goes, it seems that the King Lalibela had drawn inspiration for his architectures from the ideal image of Celestial Jerusalem. At Lalibela the city is an ecosystem and here type merges with its archetype.

TAB. 2.I TYPOLOGIES OF ROCK HEWN STRUCTURES DIVERSITY OF TYPES ACCORDING TO MORPHOLOGY

EVOLUTION OF TYPES

ORIGINAL TYPES BASE TYPES

Natural or artificial cliffs types 1

On low gradient and plain Pit type 2

Lineal type 3

Court type 4

Monolithic type 5

Pseudo hypogea 6

Natural Monolithic structures: Rock-hewn structures inside Rocks, Standing stones, natural cavities Pseudo isolated rocks, Fairiy A structures with Chimneys simple Natural monolithic monoliths Rock structures inside structures inside natural Structure inside Structures inside natural vertical Rock structures in natural Court structures in rocks underground natural pit like cavities: caves or natural cliff cavities: lineal underground cavities: with natural underground Stone cavities: Stalactites, stalagmites, cavities cavities: Dwellings, shelters, cult places inside Underground rivers and carsic allignments Cavities and potholes for standing stones and rocks Dolinas with carsic cavities caves overlooking canyons tunnels B Cromlecks settlement and water gathering inside caves with sacred use Threelithes and drips (stillicide) Lineal rock structures Mobile and in situ a)on surface: monolithic structures: Rock-hewn courts: ditches, drainages, Menhir, stelae, obelisks and Hypogea on cliffs: cavelike, pit type, lobed type, gutters; semi-arched trenches, monolithic rocks hewn or Hewn-out lobular, cell like, chamberlike Pit hypogea: orthogonal type chiselled lineal ditches, tagliata (cut) cavities or Pit like or chamber like burials, DITCHES, TAGLIATA carved rocks Apertures on natural or artifical cliffs votive shelters, sacred wells Semi-rock dwellings in b) Underground: MONK CAVES â&#x20AC;&#x201C; PETROS AND SPRING OF BIET GHIORGHIS ditches and hypogean courts C MONOLITHIC CROSS, Tunnels, cunicula; drainage PAULOS PRE CHRISTIAN HUT ENTRANCE TO EASTERN galleries FLOORS BIET GABRIEL Pseudo GROUP globular hypogea, labyrinths hypogean RUNWAYS, PASSAGES megalithic Hypogea with opening on cliff face and pothole on level structures Lobular Court quarries with monoliths Hewn-out Mines and Quarries megalithic Open sky quarries with spared monoliths cavities or carved a) on cliff; b) ditch, b1) open sky BIET GABRIEL b2) underground c) tunnels temples rocks on different shape Kurgans matrixes Nuraghi Cliff dwellings D Villages in court quarries and monoliths Trenched villages Tholoses VILLAGE ENTRANCE EASTERN COURT OF BIET GABRIEL EASTERN GROUP Talayots GROUP Trulli Use of rocks, crevices or natural cavities

INTEGRATION OFI BASE TYPES

On vertical cliffs

Rock-hewn structures on natural vertical cliffs: Rock shelters

Rock-hewn lineal natural structures: Erosion trenches

Court structures in natural hollows: Polye, dolinas, puli, Chultun

EVOLUTIONS OF BASE TYPES

ELABORATIO N OF ORIGINAL TYPES COMPLEX TYPES

Works of art, hydraulic or productive structures In cave architectures

Rock art inside natural or artificial Rock art inside ditch or gallery hypogea: Rock art in court hypogea: Rock art inside monolithic cliff hypogea: structures Tumuli, dolmens, rainwater harvesting on slopes, wells, cisterns Architectural structures, Frescoes, sculptures, vaults, impluvia and megarons, Graffiti or paintings in and snow pits, water gatherers and dispensers, aqueducts, masonry structures, workplaces, monoliths cesspits, nimphaea, ritual bathing rooms, monumental hypogean courts, workplaces Architectural structures, water MILLSTONE OF BIET PAINTINGS AND entrances, siloses, stairs and fortifications, collecting wells, cliff face cistern, GABRIEL RELIEVES IN THE SPRING OF BIET GHIORGHIS, BIET GABRIEL COLLECTOR fountains, beehives, dovecotes ADAM’S TOMB CHURCHES OF LALIBELA YEMERHANE CHRISTOS

Hypogean architecture by Cave-shape architecture: Cave dwellings temples and subtraction and hypogean churches modelling BIET DANAGHEL

Hypogean architectures with rock-hewn or built-up façades

Cliff face hypogean architecture: Cliff hypogea with carved or buit up monumental façades BIET MASCAL

In ditch hypogean architecture: Dwellings, hypogean temples and churches in ditch. Complex ditches and chambers. Multi-level burials Hypostyle hypogean structures BIET MERCUREOS archaic phase

Hypogea with architectural entrances on the level: Structures built on underground complexes and labyrinths.

G Threedimensional hypogean architecture

Semi-monolithic hypogean architecture: Complexes and monuments with sculptured façades on more sides but anchored to the bedrock, under cover or cliff BIET GABRIEL; ABBA LIBANOS, BIET GOLGOTHA MICAEL, BIET LEHEM Monolithic hypogean court architecture: Monolithic complexes with roof and four sides free from the bedrock. BIET MARIAM, BIET GHIORGHIS, MEDHANE ALEM,BIET EMMANUEL

Rock cities

Hypogean court architecture: court hypogea with spared monolithic rocks. Covered galleries. COURT OF BIET GABRIEL

Rock cliff cities Urban complexes on several levels with entrances on vertical cliffs of canyons and gorges.

Underground cities Urban complexes on several horizontal levels with entrance through wells

Trenched courts cities

Urban complexes with modelling of natural rock morphology, by means of large ditch, tunnels, hypogean courts and monoliths. Courts and terraced cities Urban complexes with development on plateau and cliff

LALIBELA

The red indicates significant types presents at Lalibela

TAB 2.II

Tab. 2.III

C BASE TYPES - Hewn-out cavities or carved rocks On vertical cliffs Natural or artificial cliff type C1 – Hypogea on artificial cliffs – Lalibela Etiopia

Caves of the monks –North Group

Petros and Paulos Cave

C BASE TYPES - Hewn-out cavities or carved rocks On low gradient and plain Pit Type C2 – Pit Hypogea – Lalibela Etiopia Sacred Spring of Biet Ghiorghis

C BASE TYPES - Hewn-out cavities or carved rocks On low gradient and plain Lineal type C3 - Lineal rock structures on surface – Lalibela – Etiopia Tagliata near North Group

C BASE TYPES - Hewn-out cavities or carved rocks On low gradient and plain Court Type C4 – Semi-rock dwellings in ditches and hypogean courts – Lalibela – Etiopia Pre Christian hut Floors in the court of Biet Gabriel Rafael

Medieval tombs cut the hut floor, this fact shows that it is built in a precedent phase

C BASE TYPES - Hewn-out cavities or carved rocks On low gradient and plain Monolithic type C5 – Monolithic Structure – Lalibela – Etiopia Monumental entrance to the Eastern Group

Monolithic Cross

Tab. 2.IV

D - Integration of base types – Hewn-out cavities or carved rocks on different matrixes On vertical cliffs and on low gradient and plain Natural or artificial cliff type – Pit type – Lineal type Da1-2-3- Quarries on open sky – Lalibela – Etiopia Quarry of megalithic blocks near Biet Gabriel – Eastern Group

This structure bears the marks left by the quarrying of rectangular blocks which were removed and taken away. Probably such blocks are still there on the site of the complex. Probably in a second time this structure was a water collecting system that conveys the water to the cisterns of the ditch

D- Integration of base types â&#x20AC;&#x201C; Hewn-out cavities or carved rocks on different matrixes On vertical cliffs Natural or artificial cliff type Db 1- Troglodyte cliff dwellings near the Eastern Group Entrance - Lalibela â&#x20AC;&#x201C; Etiopia

D- Integration of base types – Hewn-out cavities or carved rocks on different matrixes On low gradient and plain Pit type – Lineal type Db 2-3- Trenched Villages - – Lalibela – Etiopia Territorial Typology, base type – Lalibela

Market Area- Lalibela

Elliptical Neolithic Village near Matera - Italy

Elliptical structure near the North Group

The Eastern Group presents a structure characterized by elliptical ditches.

Tab. 2.V

E- Elaboration of the original types – Works of art, hydraulic or productive structures, architectures inside the caves On low gradient and plain Pit type – Lineal type E2-3- Rock art inside ditch or gallery hypogea – Lalibela – Etiopia Adam Tomb, Monumental entrance to the North Group

E- Elaboration of the original types â&#x20AC;&#x201C; Works of art, hydraulic or productive structures, architectures inside the caves On low gradient and plain Court type E4 - Rock art in court hypogea

South court of Biet Gabriel Rafael.

Inside the court there are areas devoted to structures for production activities, such as mills, tanks for the treatment of wool, storage pits and storage rooms.

E- Elaboration of the original types â&#x20AC;&#x201C; Works of art, hydraulic or productive structures, architectures inside the caves On low gradient and plain Monolithic type E5- Rock art inside monolithic structures

Relieve on Biet Golgotha

Tab. 2.VI

F- Evolution of base types – Hypogean architecture by subtraction and modelling On vertical cliffs Natural or artificial cliff type F1- Cave-like hypogean architecture:– Lalibela - Etiopia Biet Danaghel – Hypogean cave-church in the Northern Group

Biet Maskal – Hypogean cave-church with sculpted cliff face – Northern Group

F- Evolution of base types – Hypogean architecture by subtraction and modelling On low gradient and plain Pit type – Lineal Type F2—In pit hypogean Architecture: Hypostyle hypogean structures - Lalibela Etiopia Biet Mercurios in the Eastern Group – Hypostyle hypogean structure – pit type

F- Evolution of base types â&#x20AC;&#x201C; Hypogean architecture by subtraction and modelling On low gradient and plain Court type â&#x20AC;&#x201C; Monolithic type F4-5- Hypogean court architecture:- Lalibela - Etiopia

Court at the rear of Biet Gabriel Rafael

Tab. 2.VII

G- Evolution of base types – Hypogean architectures with rock-hewn or built-up façades On Vertical cliffs Natural or artificial cliff type G1- Hypogean architecture on cliff: Abba Libanos: Semi-monolithic cave Hypogea with rock-hewn façade – Eastern Group

G- Evolution of base types – Hypogean architectures with rock-hewn or built-up façades On low gradient and plain Court type – Monolithic type G4-5- Semi-monolithic hypogean architecture – Lalibela - Etiopia :

Complexes and monuments with sculptured façades on more sides but anchored to the bedrock, under cover or cliff

Biet Lehem – Eastern Group

Biet Micael Golgotha â&#x20AC;&#x201C; Northern Group

Biet Gabriel Rafael â&#x20AC;&#x201C; Eastern Group

G- Evolution of base types – Three-dimensional hypogean architectures On low gradient and plain Court type – Monolithic type H4-5- Monolithic hypogean court architecture – Lalibela Etiopia Biet Emmanuel – Eastern Group

Biet Mariam â&#x20AC;&#x201C; Northern Group

Biet Medhane Alem â&#x20AC;&#x201C; Northern Group

Biet Ghiorghis â&#x20AC;&#x201C; Western Group

Tab. 2. VIII - Aerial View of Lalibela

3. THE URBAN ECOSYSTEM

NETWORK

AND

MANAGEMENT

THE

3.1 The organisation of the site within its natural context The site of Lalibela lies at the southern foothills of Mount Abuna Josef at an altitude of 2450 2500m above sea level, on a basalt plateau upon which strata of volcanic tufa have left their deposits. The natural structural layers of the tufa present NE-SW direction, and are scarred by deep erosion furrows which from a high altitude descend to the valley below (Tab. 3.I; Threedimensional altimetry model). The slope is crossed by ditches and streams which collecting mountain rainwater convey it to the tributaries of the TecazzĂ¨ river, itself a tributary of the Nile. The three church complexes, which characterize the site, are situated on shallow ridges forming hillocks and plateaus. The focus of our attention is usually drawn towards these three monumental groups by the traditional approach to Lalibela. However, this may be misleading since it distracts us from a full appreciation of the high degree of complexity and integration between natural morphology and human activity which identify the site. This complexity is the result of a long-term process during which the natural morphology of the site has been expertly adapted to human requirements, the terrain has been modelled, spaces have been established to accommodate for a grand ideal urban project. During this long evolution process of spatial distribution, the original rock hewing craft tradition has never been set aside, and, if it has been subject to a process of evolution which has imposed changes of styles and concepts, and often sudden leaps and formal breaks, it has nevertheless remained the dominant theme of the site. Due to an hypogean base choice, the urban development does not depart nor it sets itself against the natural matrix. It is part of its very essence and it maintains a close bondage with environmental resources: water, soil, light. Within the process of construction and evolution, we may separate three great phases of spatial use which mark the history of the sites (Tab. 3.II, Territorial typologies): A) the original location phase, which utilizes sites, spaces, cavities, water courses as they exist in nature; B) the integration phase of spatial systems with the establishment of great ditches or dikes which marks an increasingly more intense use of resources; C) the phase in which the great monumental church complexes are established as a formal break, marked by introduction of orthogonal courts, which coincide with the growth of Lalibela as a medieval capital city. The choice of the original location (phase A) was due to the existence of meagre springs of water that spill out along the slopes of the tufa hills, where the tufa ends, and the basalt layer of rock beneath it emerges (Tab.3.II, 1). The first human intervention here must have been the control of water resources: the digging of gutters and canals that conveyed the water towards sites chosen as the future location of the three groups of churches. There were, however, other potential water resources: seasonal rains. To the North East a higher hill towers above the site (Tab. 3.II, 2), with its perfect conic shape strongly characterizes the landscape becoming the apex of the runoff lines of rainwater along the slopes (Tab. 3.II, 3). Violent seasonal rainfalls that cause rushing floods along the slopes in fact characterize the climate of Lalibela; these disintegrate the soil creating deep erosion gullies and furrows. The oldest settlements sought shelter at the base of the highest hill, dominant above a system of hillocks which appear as dry islands surrounded by rivulets (Tab. 3.II, 4). People lived in scattered huts and also utilized natural caves both as shelters and as sacred places. They practiced a subsistence agriculture utilizing soils soaked by floods and also a form of stock breeding based on transhumance. In those early days, scanty water supplies were provided by small springs, while great quantities of rainwater were utterly lost. However, original types gradually evolve into increasingly more advanced structures, stages of complexity and spatial articulation. In order to answer to the need for water, a new phase in the organization of site will soon emerge.

3.2 Spatial integration and economic intensification An intensification of social, technological, economic life, and spatial organization (phase B) has emerged by transforming the threat of floods into a resource: by the digging of ditches and dikes. This is the time of spatial integration of trenched huts and rock dwellings, which we can still observe in the rural organization of the Lalibela plateaus and of which traces remain in the system of ditches later deepened and elaborated, where the group of churches stands. Such ditches form part of lineal rock systems and may be divided into three types: half-elliptical ditches (Tab. 3.II, 5) which drain off rainwater protecting the site by describing an arch uphill, straight ditches (Tab. 3.II, 6) which work as canals carrying water according to gradient and conveying it to riverbeds, and the tagliate (cuts) (Tab. 3.II, 7) which capture water by being arranged transversally to the slope. The composite use of various hydraulic works creates the integrated system of trenched villages with elliptical ditches. Elliptical ditches drain the soil and keep it dry for cultivation in the rainy season. They also serve as water reservoir in the dry season and at the same time collect biological liquid refuse distributing it as fertilizer in the fields. The utilization of such system produces successful agricultural crops and stockbreeding, and generates a surplus of resources for the realization of shelters and processing technologies. Areas freed from the risk of flooding by water controlling systems, are utilized for both cultivation and settlement. Two-storied stone tower houses with pointed thatched roofs, the modern “tuculs”, are arranged into small semicircular compounds over the territory, enclosed within hedges and elliptical or semi circular drainage ditches, which also protect the fields. An outer site, situated in a periodically flooded depression and not therefore utilized for permanent structures, has become the market place. This is the meeting and exchange place for neighbouring communities; here seasonal events take place monthly or weekly for brief periods, therefore the site does not require constant protection from floods. In each of the three monumental groups of Lalibela we observe a lay out based upon the semielliptical ditch type. Rainwater descending from the great hill to the North East is intercepted by the ditch south of the Northern Group (Tab. 3.II, 4a) and by the two semi elliptical ditches of the Eastern Group (Tab. 3.II, 4a and 4b) the latter have been heavily altered recently. An elliptical village structure, whose southern part is a semi elliptical ditch, is visible in the Western Group, North of Biet Ghiorghis. Near water sources, where waters are channelled and controlled, cavities are hewn, along with tunnels and hypogean rooms devoted to the storage of grains and leather curing. Ditches also become defence systems; true rock fortifications are made both for protecting property and for grouping together in case of attack. Loftier heights are further defended by megalithic stonewalls. The system of ditches and hypogea becomes a venue for higher functions, for the management, for the temple and for the community treasury. The Eastern Group is a clear outcome of this process. The dikes system built before the medieval expansion and deepening works, clearly shows the nature of the elliptical excavations of a trenched village. Within the ditches, cliff, pit and court structure are hew out, they are organized in hypostyle halls, tunnels and cellular agglomerates (Tab. 3.II, 8). Typologies, in this phase of the works, are consistently globular and “organic”. Tunnels often show, in cross section, narrow and tall shapes. We clearly see that the network of tunnels and cells, which constitute the archaic complex of Biet Mercurios, has been hewn through by the later typology of the Biet Emmanuel court, which has a clear-cut rectangular plan. Since the court needs to be about 10 metres deeper to accommodate the monumental church, these tunnels end up on the court half way up the walls as doors or windows. These have been called look-out “tribunes” by the authors who have previously studied the site, however, the look-out tribune on the court of Biet Emmanuel, and probably the so-called Royal Tribune on the Biet Mariam court, and also other strange door-

windows opening out in the wall, can be explained with the conversion made during the construction of the orthogonal courts. The evolution of the rock-hewn artefacts evolves from top to bottom through time. Therefore works nearer the top of the plateau are the oldest whereas the deeper ones are the newest. Rubble deriving from hewing is generally piled up on the spot creating artificial mounds at the bottom of which are the debris of the higher levels, obviously hewn earlier than those at the top of the mound. The original depth of the ditches too was about 10m less than the present. It has been necessary to deepen the ditches in order that they may continue to operate as drains after the hewing of the courts of the great churches. The archaic level corresponds to the level of the outlets on the ditches walls which, as in the case of the so-called “tribunes”, form strange look-out windows on the wall, such as in the case of Biet Lehem, or are connected with the bottom of the ditch by means of steps hewn in the tufa, such as in the present entrance to the court of Biet Emmanuel, and in the entrance to the fortified guard post by the access the great trench. With the hewing of the orthogonal courts and the deepening of the ditches, these older passages and other hypogean rooms cut through by the new works; remain as gaping holes half way up the wall. The system of trenched hypogea of the Eastern Group, constitutes a sort of fortifies Acropolis provided with gates, hypogean towers and glacis. This controls the entrances South East of the site that are organized into exact typologies. Both entrances also serve as outlets for rainwater intercepted on the slopes of higher hill to the north (Tab.3.II, 2) channelled into the principal semi elliptical great trench (Tab. 3.II, 5c) and conveyed to dispensers (Tab. 3.II, 10) inside narrow and long tunnels (Tab. 3.II, 6a e 6b) towards the slope. Here they connect with the natural drainage network that decants excess waters (Tab. 3.II, 4). Their chief role was to enable the irrigation of a terraced field system situated down the slope (Tab. 3.II, 9). The southernmost entrance leads to the rock hewn court where is now Biet Abba Libanos. The floor must have been 8-10 metres higher than the level of the pit that has been necessary to hew in order to later carve the façade of Abba Libanos. The whole excavated rock front has reached therefore 20 metres in height. The excavation of a further 10 metres corresponds to the measure of the new mean depth of the ditches established during the excavation of the orthogonal courts. To the left of the Biet Abba Libanos façade a passage opens which leads to the present Biet Lehem and to the central corridor of the complex. The level of this passage is 8 metres high, but in this phase it gave onto the court and it was the guarded entrance to the fortified complex. From this we enter Biet Lehem, which is in fact a true rock hewn watchtower, the hub of a network of underground tunnels and secret passages. The tower watches over passages due West towards the present Biet Gabriel Rafael and due East towards the system of hypogea of the present Biet Mercurios. To demonstrate its strategic role, confirmed by successive reorganizations, Biet Lehem is traditionally also remembered with the name of House of Lalibela. The rear court of Biet Gabriel Rafael still maintains today its original level and design. The ancient entrance to the structure still opens on it and it is devoid of any decorative element, and its sombre monumentality is conferred by its imposing stone block and by a flight of steps. To this phase belong three pilaster strips (lesene) which frame the wall of the chamber in all its height, like two massive false pillars set against the wall. These, now badly eroded, terminate at the top where they lose their linearity like the wall itself, this proves a subsequent lowering of the structure. In the lower part the pillar strips were cut through during the insertion of the engraved windows, made at the time of the organization of the inner chapel of Biet Gabriel Rafael, and by niches and tombs. The confirmation that the floor of the court is still the original one is gathered from well preserved traces of hut floors to which palaeo-Christian graves were superimposed. The court is at less 14 metres below ground level, whereas the ditches in this area, as well as the front court itself, the result of a medieval lowering of the level, are at a level of less 22-23

metres. The court is therefore the original entrance to the underground rooms of the present Biet Gabriel Rafael that was accessible from the lofty monumental door. From the inner hypostyle halls, a flight of steps now blocked, led to the outer glacis which, protected by megalithic walls and cyclopean embattlements, commands a view of the whole valley. Boulders come from the rock quarry at the foot of the hill. The quarry is also a device for collecting rainwater. It gathers the waters from the entire slope of the hill conveying it into the ditch. Here traces of cataracts for the regulation of water flows are visible along with systems of water decantation and filtering. On the sides gape impressive cavities hewn in order to increase the volume of water storage. The system is connected, by means of narrow tunnel, to what will become, during the later phase, the deep frontcourt and entrance façade of Biet Gabriel Rafael, provided with a great underground cistern. Proceeding from the Abba Libanos court along the surface route of the open sky trench we arrive at a monumental entrance with checkpoint provided with two embattlements with pointed crenellations. The narrow passage was not so high as it is today after the medieval deepening of the ditches. Cuts still visible on the walls of the canal, made to provide access to the two pointed monoliths, show clearly the original floor level higher up. On the site we still find wandering boulders probably utilized as projectiles in times of siege. The second entrance further north (Tab. 3.II, 6b) constitutes a formidable system of control and distribution of rainwater along the slope. Access to the canal was controlled by a system of hypogean megaron-type chambers connected with the great trench by a tunnel. It is a guard post, certainly part of the archaic phase since the underground access remains suspended half way up the wall, due to the deepening of the trench where it is possible to descend only by means of tufa blocks used as steps. On the opposite side of the trench, access tunnels up the wall mark the exact height of the original floor level of the trench. We can double-check this by observing the excavation surfaces of the trench. In it we will recognize excavations of three different periods. Furthermore, at the level of the entrances, the rock face appears deeply eroded and honeycombed, to prove that it has remained for a long time at floor level and thus exposed to raising damp. Structures belonging to this phase, of globular organic cavities developed close to water sources, may be identified in the other two churches complexes. In the Northern Group we note various entrances, now almost abandoned, connected with globular underground systems of cells with rooms refurbished in later periods. The hypogean cave called of Petro and Paulos and the deserted cavities on the opposite side of the access trench to Adam’s Tomb, to Selassiè crypt above which is the so-called Royal Tribune, the church of Biet Danaghel and perhaps parts of Biet Maskal, all existed before the construction of the orthogonal courts. We clearly see how during the excavations of Biet Ghiorghis court, parts of the rock hase been spared in order to preserve existing cavities. On the East side, the court of Biet Mariam, shows a convexity exactly corresponding with the Selassiè crypt above which is the so-called Royal Tribune now exposed by the hewing of the court. On the south side the evenness of the court is discontinued by a cube of spared rock left in order not to destroy an existing cavity that had been partly reworked to create the church of Biet Danaghel. These rooms formed a system of cavities related to secondary entrances and with the outside slope situated between the two monumental entrances. The area on the right of the original entrance is still a large water cistern. The protective trench has cut through the tunnel connecting with other similar cells at the time of the building of Biet Miriam. Since the trench rests at a lower level than the aforesaid rooms, now the two ends of the tunnel form windows facing each other on either side of the trench. Lower down the original entrance has been re connected to the court by means of a stone slab forming a bridge on the trench. On the slope there are still clear traces of archaic hut floors cut through by paleo-Christian graves. In the Western Group traces of archaic dwellings are recognizable in the ditches that connect with the natural stream of the River Ghiorghis by means of a hydraulic device that is still today a sacred baptismal font. The entire area included between the three sites has been subject to a constant

process of reclamation and control of the water supply by means of semi elliptical ditches, straight canals and tagliata (cut). The latter, contrary to the straight ditches, which follow the maximum gradient of the slope in agreement with the natural course of streams, are laid transverse across the slope. They therefore intercept all superficial water flows creating dry areas below them. Two precise tagliata are recognizable South of the Northern Group (Tab. 3.II, 7째 e 7b). They are probably part of the complex water capturing and clearing system related to the elliptical trenched village structure of the Eastern Group, North of Biet Ghiorghis. A third tagliata is recognizable towards the end of the slope between the Northern and the Western Groups (Tab. 3.II, 7c). This if located uphill from a long tagliata that connected the ditches of the two groups (Tab. 3.II, 7d). This tagliata is now completely full of debris and it played a fundamental protection role. On the platform of the Geographical Information System (Tab. 3. III Hydrographical simulation of torrential rains) a torrential rain has been simulated on the site. The flow of rainwater in rivulets have been analysed and the way water invades and washes away arable soil making the land useless has been enlighten. Simulation takes into account of the direction of ditches now in operation. These still protect, but only partly, monumental complexes. The lack of maintenance and the blockage of many ditches cause new flows, infiltration and stagnation of rainwater. All the central area of the site in particular is subject to flash floods and torrential floods, mainly due to the silting up of the main tagliata (Tab. 3.II, 7d) that is completely blocked and no longer has a protective function. 3.3 Monumental transformation and construction of the urban ecosystem In the geomorphology map, relevant elements of the spatial structure have been identified. It is interesting to see how the high hill to the Northwest presents at its foot, in the direction of the site, alluvium sediments whereas frequent landslips characterize the southern slopes. The erosion caused by rainwater is apparent and the site, having rationalized the runoffs of the slope in a direction NW-SE, has become a regulating system of the slope and has thus protected the soils. It is likely that in ancient times extensive terraces existed where remains of archaic cyclopean walls are still found today. The very ancient olive, thuja and juniper trees, placed in strategic points naturally subject to soil erosion and landslides, must have played a fundamental role in the protection of soils and in environmental conservation. The terracing technique has recently been revived with a project of nature engineering carried out to the south for safeguarding the road. The realization of terraces, cultivations and tree plantation are fundamental for the environmental conservation of the site. Basalt rock emerges in its natural state to the south whereas elsewhere it is covered by a layer of volcanic tufa. Wide areas of tufa rock artificially exposed are prominently visible near all the monumental areas and by the ditches. These areas played an essential part in the modelling of the site. In fact, excavations began with the exposure of the tufa rock that in this way could also help to capture running water and to collect watercourses running down denuded slopes. Between the Western and the Northern Groups there is a long slope used for intercepting water by means of two tagliata. The water-capturing slope and tagliata are in close relationship with the reservoir below the modern road. A further morphological characteristic consists of the great mounds of rubble that form true hills near every significant area. They bear witness to the massive hewing work carried out through time, they are our indicators for the discovery of areas of interest still unknown and represent a true extraordinary time capsule of archaeological information. In fact as said above, when hewing takes place, rubble grows from bottom to top thus preserving a precise stratigraphy record of the work. The most important modelling work is carried out in monumental church areas that concern the reorganization of the trench system. An exam of these works brings to the fore how the two systems are precisely connected and how the whole area

has been subjected to a programme of space modelling by means of excavations of titanic proportions. This is the phase of medieval monument creation relative to the creation of Lalibela as capital city (phase C). The lay out of the great basilicas constitutes a drastic architectural rift. Structures are now characterized by orthogonal plans, monumentality, East-West orientation and monolithism. Such choices are not solely motivated by an effort towards representation and grandiosity, but by a spiritual need and by concrete social and cultural reasons. The monoliths, which have made the monuments of Lalibela famous, find their explanation in cultural practices that are deeply rooted in the sentiment of the community. Popular tradition demands, in fact, that religious piety be manifest through prayer and rituals taking place outside the church itself, thus creating the need for adequate outside spaces. Among these practices there are ritual processions encircling sacred places. This explains why the church should be free from the mother rock on all four sides and therefore be a monolith. This is the reason for monuments in caves to be semimonoliths, provided with a walkway all around them and also the reason for the great effort put in the transformation of older structure into semi-monoliths. The increasingly more complex typology and the quality leap are to be seen in the context of a long-term process of environmental organization. The great orthogonal courts (Tab. 3.II, 11) with the monlithic basilicas of Biet Emmanuel (Tab. 3.II, 11a), Biet Medhane Alem (Tab. 3.II, 11b), Biet Mariam (Tab. 3.II, 11c) and Biet Ghiorghis (Tab. 3.II, 11d) completely transform, albeit in faithful observance of the principles and environmental aims, the morphology of the three groups and determine an increase in scale. The site, in its new role of kingdom city and spiritual centre, does not forsake its original environment. It respects its laws; it changes according to precise canons imposed by the appropriate use of natural resources thus creating an urban ecosystem. The monumental development does not involve the orthogonal courts only; it also reorganizes the ditches and increases their depth. (Tab. 3.II, 12) according to the depth of the courts that needed to accommodate the basilicas. The whole system has been organized in such a way as to allow the drainage of water by gravity thus keeping the great courts dry and connecting the system to the drainage network on natural watercourses. In the Geomorphology plate (Tab. 3.IV Geomorphology Map) the highest and the lowest contour lines have been highlighted. This has enabled us to understand the workings of the gravitational network upon which the urban lay out is based. The analysis also brings into evidence the components of the urban structure (Tab. 3.V, Urban Structure). Drainage, vertical ditches, trenches, tagliata and monumental areas, conjure up an urban design with clear organizational lines and a faithful contemplation of natural environment. Beside the orthogonal courts, a precise scheme has involved all existing structures and the entire urban lay out. A clear example of this process is illustrated by the excavation of Abba Libanos which has involved the deepening of the original entrance court, structural alterations to Biet Gabriel Rafael, the transformation into semi monolithic structure of existing hypogea and the introduction of a new system of passages and monumental accesses (Tab. 3.II, 13). In the Western Group the need for draining the court of Biet Emmanuel, about 15 metres deep, has generated, as said above, the need for deepening the great trench. This has in turn required more alterations throughout the area. Even the inner smaller trench has been hewn further in this phase. In fact, the two mounds of debris resulting from the excavation of the trench, appear cut through by the latter. The levels of earlier cavities are easily seen since in the new excavations, there are spared blocks and rock glacis marking the old levels. The new trench connects with tunnels and underground passages constituting a system of defence and access that creates the monumental entrance in alignment with the main faรงade of Biet Emmanuel. In Biet Gabriel Rafael the most prominent transformations concern the switching around of the main entrance front with the creation of the faรงade that acquires a monumental dimension with the deepening of the court and the modelling of two massive plinths set against it. An attempt to make the

complex a monolith consists in the hewing of a trench, which encircles the Sancta Sanctorum, which has been abandoned due to a decompression effect and the risk of collapse manifested during the works. This is probably not unfinished work, may be that the objective was only to enable access to this part of the church externally by walking along the trench. A similar architectural solution is visible in the wall hypogea of the Degun crypt, and in the church of Debra Maryam of the Qoqor falaise, both situated on the Garalta plateau in the Tigrai, to enable pilgrims to pray outside but near the sacred sites, only accessible internally by priests of a superior order. At Biet Gabriel Rafael further interventions concerned the thinning and lightening of the roofing. Inside the inner court we clearly see how the lower windows are a later addition, later than the first realization of the complex, which generally speaking preserves its character of palacefortress, provided with considerable self sufficient systems of water collecting and storage situated in a commanding position of the whole valley. To the older entrances to the groups a new network of walkways and monumental entrances are added and these characterize the new integrated urban dimension of the site. The main axis of approach to the city is oriented SE-NW and matches the transit systems North to South of the Ethiopian ridge, as intercepted by the city of Lalibela. This direction is marked by the central axis directly pointing at the monumental entrance South to North of the Northern Group. Another route reaches the Western Group and, beyond this, the market area where by means of a monumental road one can reach the Western monumental entrance of the Northern Group, whose landmark is Adamâ&#x20AC;&#x2122;s Tomb. The three Groups are thus united by a design which precisely organizes them like three arms of a cross perfectly matching the cardinal points. At the centre of the cross, which is also the focal point of the canals, and of the natural source of the torrent called Jordan, a monolithic cross has been carved (Tab. 3.II, 14). The monument bears a great significance both as a symbol and as a territorial mark; as a religious sign, it makes an environmental warning statement. The monolithic cross has been carved out of a portion of rock especially spared during the digging of the ditches. It marks the site of hydraulic works and at the same time it is an integral part of them. The ditches are at one time routes, hydraulic device, defence, urban border and symbolic marker. These are the vital and fruitful lymph; they mark the existence and the progress of the city. They swell with floodwater during the rainy season and become dry walkways during the draught. They store water in their secret underground cavities, making it available to the terraced fields and the crops, enabling with their contribution, wisely managed, the growth of crops, the ripening of fruits and the flourishing of the landscape. Despite of their multiple roles, they represent the unchanging significance of the city, its story forever engraved in the rock. Generally, in the historic built city, the walls are the element that immediately expresses the urban perception and identity. We are therefore used to seeing an ideal model of formal value and of urban community in the walled city. In the hypogean system, where all is reversed, and the environment must be perceived in negative, the dug out trenches assume this role. In order to identify the urban form of Lalibela it is necessary to comprehend this new upside down dimension. In Table VI (The trenched city of Lalibela), the network of ditches matches exactly those identified as certain, in view of the fact that only a graphic elaboration has been made of the survey in the plate illustrating the urban structure. With the graphic rendition of the ditches, the harmony of the urban form become manifest: the design of Lalibela as trenched city. Lalibela is the outcome of a grand vision inspired by a spiritual design realized by the relentless endeavour of a community that, in that design, has found its identity and cohesive force. Of this work we see today the most obvious stone works, but from its rocks water spilled out, fields were cultivated between the crags, grains were stored in its caves. The dream came true with a vital system in an Earthly Paradise. Lalibela was a garden city where waters flowed, flowers blossomed and life pulsed.

The synthesis plate (Tab. 3.VII, The urban synthesis) is a reconstruction of this image. The hollow space of the ditches is filled with meanings, with relationships, of identities and so the spirit of the place materializes, the city of Lalibela not as an aggregation of monuments, but as an integrated ecosystem, the mirror on this Earth of the Celestial Garden.

Tab. 3.I - Three Dimensional Altimetry Model

Tab. 3.II Territorial Typology

Tab 3.IIa – The Western Group

Tab. 3.IIb – The Northern Group

Tab. 3.IIc – The Eastern Group

Tab. 3.IIId - Hydrographical simulation of torrential rains

Tab. 3.IV

Tab.3.V

Tab. 3.VI - The trenched city of Lalibela

4. ANALYSIS OF DECAY FACTORS A characteristic of the Lalibela monuments is that they are hewn out of rock consisting of soft tufa that rests upon a bedrock of basalt. They therefore belong to the context of rock-hewn architecture and, within it, the peculiarity of the Lalibela complexes is that they are monolithic. To be precise, only some of the monuments are true monoliths or, in other words, separate from the mother rock on four sides and top. Having said that, there are at Lalibela specifically monolithic structures, others are semi monolithic, and others still are hypogean rock shelters, cliff dwellings or belong to other typologies of hewn out architecture. In the context of this terminology, classification and definition for the great architectural variety, directs conservation interventions, since structural conditions, the nature of cracks, deterioration factors and other risks present a variety of situations typical for each of the various typologies. Generally speaking, the structural peculiarity of rock-hewn architecture, as against the built up, lies exactly in the fact that the former works is in close relationship with the mother rock. This determining factor carries both advantages and disadvantages. Working as a completely cohesive system, it has greater chances to support and distribute loads, even in the presence of factors such as shocks, it is however subject to other kinds of risks since the architecture is affected by dampness, infiltrations, movements and also subsidence of the rock system to which it is connected. The more rock-hewn architecture is monolithic or, in other words, free from the mother rock, the fewer are the negative effects caused by structural problems affecting its environment. Having said that, in such cases, problems of a structural nature increase. Generally speaking, a true monolith, being the result of hewing a single block, has pillars, arches and vaults all connected between them and solidly anchored both to the bedrock and to the ceiling. Structures, therefore, are not subjected to the effects of loads and are less sensitive to possible shocks. Nevertheless, very large monolithic structures, as it is the case of Biet Emanuel and Biet Meidhane Alem, suffer greatly from seismic shocks, due to the oscillation of the upper parts, where the enormous load of the roof bears upon an architecture that is free on all four sides from the mother rock. Furthermore, a typologically monolithic work is often, from the structural viewpoint, in a condition of only apparent monolithism. In fact, natural layers of discontinuity and cracks, impair inner cohesion making the monument similar to architectures based on static, with a load distribution of a pushing kind. Cliff dwellings and rock shelters, which we include among monoliths, are safer from seismic hazards in that they constitute a whole with the mother rock. They are however subject to specific pathologies due to the fact that they form an integral part with the cliff with which they share and exchange dampness, mechanical deformities, and possible risks of catastrophic collapse due to situations of subsidence of levels, or collapse, such as in the case of Biet Abba Libanos. Pathologies of the monument depend on deteriorating factors generated by erosive conditions, which are both geological and biological, and also to deteriorating factors of a structural nature. Decay factors in the churches of Lalibela may be synthesized as follows: 1. All churches present a range of structural and deterioration problems for each single situation, and each monument constitutes a case study in its own right, due to differing volumes, spatial positions, relationships between negative and positive volumes. 2. The common element uniting all monuments is the high discontinuity of the rock in which the churches are hewn. 3. Generally such discontinuities have been used during the hewing of the monuments.

4. Discontinuity of levels may have more or less serious reflections upon the state of the monument according to each individual case. Generally speaking if the level of the geological strata of the materials is horizontal, there is no problem, whereas when the strata are at a tilt the static quality of the artefact is undermined. 5. Albeit to a different degree in each specific case, in all cases the water factor carries a high responsibility in the alteration of materials. Water, therefore, shares a high degree of responsibility in all decay phenomena, with varying degrees of seriousness. For example the percolation of water produces serious problems when encountering unevenness, even natural, of the materials, whereas alveolizated effects are common in all churches, even when very extensive they do not however undermine structures since the monuments are monolithic. 6. Roofs are always very heavy and constitute an weakening factor for the monuments especially in Medhane Alem, Abba Libanos, Biet Emmanuel and Biet Mariam 7. Seismic hazards constitute another common factor involving all Rock Hewn Churches, albeit reactions to earthquakes have been different due to the structural peculiarities of each church. 4.1 Analysis of the erosion factors Deteriorating factors of a geological and erosive nature vary according to place, exposure and nature of the rock. Their effects on a monument depend on the typology of the monument itself. According to the way hypogean structures are hewn from the mother rock and the degree of exposure to weather of carved structures these may be grouped into three great families: cavities hewn horizontally into a cliff face or artificial wall; vertical pits on level ground; monolithic structures or carved walls. Specific types present pathologies according to their place within these families and to their place in the general picture. 4.1.1 Cave hypogea on cliff faces or artificial walls Cave hypogea suffer from all pathologies connected with the situation of the rock face or slope in which they have been hewn. The latter is physically subject to gravitational subsidence outwards, which may be accentuated by the morphology of the geological layers or by discontinuities existing in the texture of the rock. Erosion phenomena of a meteoric nature depend upon water infiltration (A) into cavities due to the nature of the rock, to the existence of fractures, to the conditions of drainage and aeration. The presence of an artificial cavity alters the distribution of stresses inside the rock. Decompression occurs which favours cracking, detachments, water infiltration and of other erosive agents such as roots of trees and guano. Inside cliff or wall hypogea the tendency of the rock to be sensitive to decompression phenomena (B) in an outward direction causes series of vertical quasi-parallel cracks towards the canyon front. Inside the cavity, the most vulnerable part is the ceiling of the cave that may present sagging and erosion phenomena. In the first instance upper decompression causes a sagging of the rock strata that may cause the collapse of the structure. In the second instance the erosion of superficial layers generates the so-called erosion bells reducing the thickness of the ceiling and weakening it. The lack of air and water infiltrations cause physiochemical erosion with swellings, peeling, decay of surfaces and biological erosion caused by moulds and other invasive agents.

Biet Gabriel: Court and lateral cisterns. In the cavities the presence of an artificial cavity alters the distribution of stresses inside the rock. Decompression occurs which favours cracking, detachments, water infiltration and of other erosive agents

In the case of cliff or wall hypogea the tendency of the rock to be sensitive to decompression phenomena in an outward direction causes series of vertical quasi-parallel cracks towards the canyon front

Rear Court of Biet Gabriel Rufael

4.1.2 Pit hypogea Pit hypogea are affected by the geological nature of the excavation level. Decompression (B) caused by the excavation of the cavity manifests itself with pushing reactions chiefly on the walls that may show swellings and collapses. Upon the ceiling the same factors are at play with sagging and erosion in cliff or wall hypogea. More important are the risks connected with water percolation (A) and with biological pathogenic agents. In fact, in these hypogea the possibilities for drainage and airing are scarce. Massive pillars that form hypostyle halls often support the ceiling. Upon these the weight of the strata above is a crucial factor. Pillars may suffer from decompression and show a typical swelling half way up: a symptom of structural pathology.

Biet Mercureos Pit hypogea are affected by the geological nature of the excavation level. Decompression caused by the excavation of the cavity manifests itself with pushing reactions chiefly on the walls that may show swellings and collapses.

Biet Mercureos Pillars may suffer from decompression and show a typical swelling half way up: a symptom of structural pathology.

4.1.3 Monoliths and sculptured walls Monoliths, beyond the pathologies which they share with the above types, and which occur in the hypogean environment, suffer from erosion phenomena that derive from the exposure of their walls to atmospheric agents. The most relevant meteorological agents are the wind, variations in sun, water and temperature. Winds (C) carry sand that causes corrosion or abrasion of surfaces leading to decay and loss of material. Alternate exposure to sunshine causes expansion by heat that accentuates such phenomena. The most serious erosive agent is water (A); this may derive from rain or from the soil. Rainwater alters the chemio-physical composition of the rock, it dissolves it, it penetrates the cracks, it carries biological pollutants and agents causing disintegration accelerating decay. Underground water causes decay effects typical of all monolithic and wall structures. This manifests itself as a strong erosion which affects the base of the monument. First by creating a honeycomb effect on the rock then with other ever increasing decaying affects leading to the formation of deep erosion cavities called taffoni. This is due to rising damp that is sucked up from the ground to the inner micro-cavities of the rock. Water migration inside the monument and its evaporation on its surface causes the disintegration of bonding substances and thus dissolving the rock. Decay remains confined to the lower part of the monument both because there is a physical limit to the possibility for the water to rise, and because lower parts are generally in the shade and more prone to damp conditions. When the floor of the monument is loaded with organic pollutants these are carried by water that increases its deteriorating potential, leaving typical black stains on the surfaces. The condition of the monuments of Lalibela of creating monolithic systems inside courts connected by great trenches

increases the risks of erosion in connections with such structures. In facts the great ditches and rock-hewn courts represent a complex drainage network which channels and discharges water. The system is still largely unknown and blocked by debris and rubbish. Such conditions prevent the network from functioning for the drainage of water thereby increasing stagnation phenomena at the base of monuments, favouring rising damp and polluting agents.

Biet Mariam The most relevant meteorological agents are the wind, variations in sun, water and temperature. Winds carry sand that causes corrosion or abrasion of surfaces leading to decay and loss of material First by creating a honeycomb effect on the rock then with other ever increasing decaying affects leading to the formation of deep erosion cavities called taffoni. This is due to rising damp that is sucked up from the ground to the inner micro-cavities of the rock

Biet Mercureos Water migration inside the monument and its evaporation on its surface causes the disintegration of bonding substances and thus dissolving the rock. Decay remains confined to the lower part of the monument both because there is a physical limit to the possibility for the water to rise, and because lower parts are generally in the shade and more prone to damp conditions

Tab. 4.I – EROSION FACTORS TYPOLOGY – Synthesis

STRUCTURAL ANALYSIS

5.1 Structural issues characterizing the rock-hewn complex of Lalibela All the churches are the result of an incredible, patient digging work, carried out by removing material from the tufa-like rock thus realizing an astonishing “negative” architecture, imitating the classical basilical or central-plan models, with a strong influence from the local art (Axum). Some churches are clearly the outcome of manipulation on previous types of organization (a kind of fortress in the case of Biet Gabriel-Rafael), others have developed on primitive rock hewn constructions. The predominant type is the rock hewn one, with all four sides and the space above the roof free from the rock. The roof is obtained by modelling the top surface of the rock and therefore its extrados rests at the same level of the adjacent country level. There is also the variation “beneath rock”, characterized by four sides dug in the ground but a “natural” covering which is embedded in the overhanging rock. Finally, some buildings present one or two sides (and, sometimes, even the roof) embedded in the tufa-like rock. Therefore the embedded sides are not worked. The main point, from a structural point of view, is that these constructions, resulting from the removal of rock material are, in facts, monolithic blocks and therefore mechanically behave in a very different way from traditional buildings. These are in fact created by assembling separate elements and blocks and thus constitute wholly discontinuous entities. What we should immediately acknowledge is that these churches are today, and probably were from the beginning, crossed by a system of crevices and separation surfaces that characterized the rock sediments before the digging work, and that now define, as a random consequence, the disposition and weak belts and/or discontinuities. A curious and dangerous consequence of this is that these buildings are discontinuous solids, but in this case the discontinuities are not resulting from a known constructive process or from alterations and kinematic motions triggered by defects in the construction or occurred later (that for us are clearly readable as a result of known rules and solutions). The lack of continuity in the rock-hewn organization derives from consolidated geological aspects that are often hidden until the excavation takes place. It becomes very difficult, from a structural point of view, to evaluate the consequences. In fact, no doubt, the absence of monolithic structures obliges us to interpret the structural mechanism as bound mechanical systems but it will be necessary to understand which discontinuities are active, which are totally inert, and which are responsible for thrusting actions and produce mechanisms. In short, our knowledge acquired from traditional building cultures must be abandoned and the system’s behaviour must be reinterpreted following the few clues that it provides and that can be summarized in the disposition and size of the fractures and the imbalances. In this interpretation process a contribution from geological experience is essential and substitutes the mastery of the constructive processes, which is now practically replaced by the dynamics of natural processes. In the light of all this we may deduce that the monumental complex of Lalibela is characterized by: 1. The realization of the churches through the internal digging of blocks or layers of tufalike rock, sometimes based on basalt flows that present relevantly discontinuous surfaces. These surfaces, internal to the thick blocks of rock, are often tipped, sometimes horizontal and, in some superficial layers, chaotic. 2. The entire complex has been, for centuries, constantly exposed to weathering, particularly rain, lacking any form of protection apart from the same rock.

3. The “building” process, although refined and astonishing in its appearance, presents work on deep surfaces, both on walls and on horizontal separating structures, as a constant and inevitable element that influences the mechanical behaviour. In particular, while the depth of the vertical supports (including the numerous pillars) is only advantageous, the width of the orientations, and especially of the roofs, creates a structural system that undergoes considerable stress. The result is an organism that in time will be subject, for the above reasons, to considerable alterations. In fact, supposing that the apparent discontinuities of the rock were not there at the moment of the excavation, it is reasonable to say that for its position and its status of stress (i.e. “under pressure”) influencing the mechanics, it will in any case present vulnerable surfaces in the future. Therefore, the constructions will be the first to be affected by any alterations of the material deriving from water infiltrations. At this point the swelling up and the contractions of tipped surfaces will determine their sliding and detachment. The fabric, perhaps originally “monolithic”, is no longer so and will have to deal with the laws of statics and assembled body balance. It is at this point that the rock-hewn construction starts paying a high price. The thickness of the surfaces that once guaranteed protection from rain and corrosion now turns out to be heavy and statically precarious thus stressing the vertical supports. In this situation, characterized by a considerable strain, most important is the passage to a disposition in which the systems may become thrusting and the thrust line may start tipping. It is clear that such an evolution may sometimes find, in the oblique disposition of the rock layers, an element that multiplies the effect; the arches that were originally only “drawn”, are now cracking and putting pressure on the springers, and the same happens in the engraved vaults; in short, the entire artefact has changed and has become something different from the original. There are therefore two factors contributing to the definition of the static system, we can define them both intrinsic and extrinsic to the construction. They refer to: 1. The disposition of the dead loads, function in geometry and material in what we can call a standard system (vertical loads). Another phenomenon also adds to this 2. The seismic movements significantly stress a building with the features we have described. Its major weakness lies in the excessive thickness of the roof: if an earthquake should occur this will tend to oscillate with a devastating consequence on the wing walls which will be subjected to several motion rules, and which are already vulnerable where separated in different blocks. 3. A final fragility element is added by the reaction of the rock mass to the removal of material: depending on the different levels of rock homogeneity there may be discontinuity surfaces, prevalently vertical, connected to internal co-active systems that were present at the moment of the geological origin. A circumstance that may support this assumption is the proximity of the site to the Rift tectonic discontinuity, responsible for today’s active processes of plate distancing at the rate of several millimetres a year. The loss of natural containment exposes the parts that are nearest to the engravings which undergo “decompression” fracturing processes, that is to say a loss of static confinement regime; moreover, as a consequence of bold digging operations, a significant modification may occur in an acquired stress situation. 5.2.Synthesis of structural vulnerability We can thus summarize the structural vulnerability of the monumental site of Lalibela. Firstly we will refer to all the churches in general and later we will describe the single situations

according to precise schemes. The aim of this detailed survey is exactly that of defining the diagnostic situation for each church. General features: 1. The supporting structures are crossed by discontinuity surfaces that have in time transformed the artifacts in assembled structural systems that are often thrusting 2. Water has a devastating effect on the conservation of the churches; it seeps through roofs and walls, causing volume variations and triggering a series of movements resulting in fractured surfaces. 3. The material appears deteriorated in many places as a consequence of the physical and chemical modification due to weathering; its mechanical properties are highly variable even within the same building, nonetheless being a good building material, its performance in resistance is very rarely compromised. 4. The dimensions of the buildings are large; the roof in particular is exceptionally thick (probably the intention was to confer strength) requiring an equivalent thickness on the vertical members; this may turn out to be critical, especially in terms of balance, when the fractured system becomes thrusting. 5. The buildings have been, and will be in the future, exposed to significant seismic events; their structure (see point 4) makes them extremely vulnerable to such events. 6. The discontinuity solutions that were detected within the material of the construction, are also present on the adjacent parts of the rock mass; this means that landslide movements may be active and that destabilizing actions may be transmitted to the rocky systems that act as roofing. 7. Unlike the acquisition of scientific data concerning the geological and geotechnical sector, there is a lack of information concerning the strictly structural level that describes, for example, the evolution of fracture patterns, their real dimensions and disposition; this kind of knowledge is essential to make a diagnosis possible. 5.3 Fractural patterns and static consistency in some relevant cases We have carried out a structural survey of the churches with the most complex architectural features. The aim of obtaining a kind of â&#x20AC;&#x153;pathology frameâ&#x20AC;? was therefore achieved to allow comparisons and recurrent similarities, or peculiar aspects, connecting the deficit to the reproduction of certain constructive or typological conditions. 5.3.1 Biet Medhane-Alem The church of Biet Medhane-Alem, belonging to the first group of rock-hewn buildings, is the most outstanding. Entirely separated by a deep trench from the surrounding tufa-like bouder, it is characterized by a basilical plant, based on 5 naves, the central one covered by a lancet vault engraved like a barrel and with a saddle-roof. The fashioned rock block, that acts as a roof, only produces for about 2 mt. on the lateral walls and is therefore supported by numerous pillars that mark the perimeter of the fabric. The members derived from the digging work are very large, but what catches the eye is the thickness of the roof (reaching 5 mt.). It is a known fact that the church has undergone several damages and restorations. All the walls testify this; what we are mostly interested in is the uneven history that lies at the bottom of the gradual substitution of most of the external pillars and the restoration of some portions of the overhanging roof-gutters, positioned on the long side of the roof. First of all it must be said that considerable damages have long ago transformed the building into a very different structure from the monolithic block the diggers intended to obtain. Today the system mechanically behaves like a traditional building, in fact it is supported by perimeter walls, internal archways and vaults, all showing transversal cracks. Particularly striking is the high price paid by the system of pillars, for the most part collapsed or replaced.

Searching for useful clues (symptoms) useful to formulate some hypothesis on the damaging mechanisms, we observed the fracture system in the monument and some important indicators that were positioned by Arch. Angelini in 1968. What seems clear is that there are several types of damages that can be divided in three fundamental homogeneous classes according to the movements they are related to. 1.

The first and most important class is the one grouping the damages on the short façades of the building (front and back), that are concentrated around the corners of the box, with a diagonal direction. They all have the peculiarity of being wide at the top and narrow at the foot. This unequivocally indicates a rotatory motion around hinges set near the base of the walls, originated from translational motions of the roof mass. Such manifest effect denounces a mechanism that originates from the high belts of the building and significantly disrupts the external support system, which is highly stressed for not being able to go along with the translational motion without braking. Therefore, the first impression regarding the collapse of the pillars that support the roof must be rectified and interpreted as a secondary phenomenon, serious but induced by a previous movement of the roof pitch. The last category includes the damages on walls, arches and vaults, mostly inside the church, that testify the need for the system to adapt to the new configuration, and its consequent fractioning into several parts, turning into a structure with all the features of thrusting built systems.

In this framework very grave local situations are identified: a. the detachment, with escape from axial configuration, of the pillar in the back façade (a phenomenon testifying the lack of a functional role for some columns which are clearly “hanging” from the roof block); b. the split architrave that connects the roof with the pillars at the far south-east side. Finally, it is interesting to follow, on the external surface of the roof, the previously described fracture systems: this perfectly corresponds to the cracks on the façades, the symptoms of a mighty evolutionary mechanism. Wanting to formulate a hypothesis that explains the sequence of the detected kinematic motions, the first conjecture is that something weakened the structure from the beginning, encouraging the separation and sliding of surfaces that were present since the beginning. The triggering cause is no doubt water; in relation to this it is instructive to look at the delicate and intelligent rainwater run-off system designed on the roof extrados. Here a succession of nicely carved and moulded arches, embossed on the two pitches of the roof (some interpret it as an Axummite picture), indirectly creates an articulate system of sliding canals which drain the water to the corners of the building. However, in time the defensive capacity of the mass, although thick (and probably intentionally so very thick!), has yielded to seepage, becoming a dangerous and destabilizing factor. For all we have described we suppose that the most probable event was an earthquake, this would explain the fracture pattern we observed. This consideration should be cause of alarm since the great thickness of the roof may turn into an oscillating mass of devastating proportions. While we can find validation for this consideration in Arch. Angelini’s description, in his precious notes about the damages he found (witness that gains even more value thanks to the system of indicators he skilfully set on the monument), the chains that were positioned then were not as effective as expected. In order to be effective these should contrast the motion at the top and not be fixed in correspondence of the abutments of arches and vaults, that is too near to the

hinges. Such safety measure results ineffective in contrasting the possible undulations of the roof, even though, in the present situation, they are on no account to be removed, since they have come to play a part of the evident transformation of the entire structure within a thrusting system, albeit only for vertical loads, typical of arched solutions. What is dramatically still not dealt with, is the form of intervention to contrast the seismic movements (which is not easy because of the enormous masses that move on the top); one also starts wondering as to what extent the continuous and recurrent lamentations on the ineffectiveness of the actions undertaken to protect the building from the rain, are justified, if nothing is done to stop the building from opening and closing in response to seismic movement, there is obviously no mortar or cement that can be applied to the cracks to stop this process. 5.3.2 Biet Mariam The church of Biet Mariam, at the centre of a wide forecourt hewn out of the tufa-like rock, it is a basilical building with a three nave plan and an upper semicircular gallery. Refined in rich carved and painted decorations, it is a well proportioned building but not too big; it is characterized by three external arcades carved in the rock. The static situation appears coherent with the description made by Margottiniâ&#x20AC;&#x2122;s mission; the numerous damages do not denounce a rapid evolution or aspects of instability and are therefore not alarming. It must be said though that the church presents some past symptoms of instability, basically two featuring elements: a) evident repairs of cracks, localized on the four top corners of the box, show some outwards rotation attempts; furthermore we can observe some diagonal toothing losses on the faĂ§ades. a. The instability and incoherence of the external sides of the arcades, subject to kinematic and discontinuity movements and for this they have been tied back o the main, more stable, body of the building through the insertion of several metal bands or through their total reconstruction. In this case also the complex seems coherent but the seismic motions and the weight of the roof as well as the weakening of the monolithic status as a consequence of water infiltrations and of the walls worsen its conditions. From this point of view the solution of covering the arcades makes things worse, at least for the time being because they have a flat surface not conducive for a quick drainage system, as the small ledge of the roof fails to shield the walls of the central body. The limited dimensions of the building, in this case, and the limited proportions of the volumes have undoubtedly protected the fabric of Biet Mariam. The only weak point is, from an antiseismic point of view, the great gap in the volumetry and its associated rigidity between the main body of the church and the external arcade system, which is much frailer and most of all receives the oscillatory action of the major mass. This forces on the faĂ§ades dangerous detachments and critical areas (in the same places where the pressure of the upper bodies is also bearing)

5.3.3 Biet Emmanuel The church of Biet Emmanuel, of considerable dimensions, quite similar to those of MedhaneAlem, presents the same basilical plan that is now distributed in three naves and has a saddleroof that is badly deteriorated and which has a very small ledge. Here the spatial distribution design is more complicated, being characterized by a central nave with a double height closed by

a barrel vault, with the terminal spans reinforced by consistent walls (the splat one having a double volume and hosting the drawing of a dome over the place where the tabernacle is). Finally, a gallery is inserted between the aisles and the roof. The general impression is that of a solid building where once again the dimensions of the roof are impressive (more than 2.5 mt. thick) especially if examining its section and comparing it with the dimensions of the walls and central pillars. The plan shows a considerable percentage of built areas, as compared to the empty spaces and to classical basilicas in general. If such a artefact had continued to be monolithic it would probably have endured in time without any problems, being similar to a natural rock. But as it happens, it is crossed by fractured and discontinue surfaces, particularly evident on the roof. As we have explained earlier, a building with such mass distribution becomes, mechanically speaking, inevitably fragile when separated in several parts, since it is obliged to find new ways of unloading the weight on the ground, according to the rules of balance, typical of blocks systems. But now there is a high degree of strain (for the standards of traditional buildings), conditioned by discontinuity and sliding surfaces that become very dangerous when slanting. The fracture pattern, that we observed mainly from the outside because of the scarce light inside, is characterized, as the previous reports confirm, by an wide crack in the barrel vault on the vertical symmetry plan, by several fracture systems (also with a vertical direction) on all the perimeter walls, by oblique damages in the vicinity of the corners of the box and by the opening of hinges and cracks on the arch systems and on the internal ceilings. The reflex of the described complexes involves the entire system of the roof boulder. We are facing an artefact that is evidently undergoing a crisis, where the results of our survey seem to indicate a general behaviour of the system related to three main phenomena: a) The opening of the building in a transversal direction, as induced by the action of the horizontal components of the heavy roof masses that have now become thrusting. b) The stress on many supporting vertical elements, i.e. pillars but also parts of walls that are strained to the point that, as the vertical damages indicate, flakes of stressed material become separated by parts that are less subjected to strain (this should be interpreted as if real pillars were created within the walls) c) The reaction of the building to seismic motions (confirmed by Angeliniâ&#x20AC;&#x2122;s statements about the presence of damages with major cracks on the top). In this case we seem to be observing the reassessment of a seismic problem, causing a fragility that is mostly related to the classical functioning of a monumental building. A possible explanation may be (with the exception of the circumstances related to the propagation of the undulation) found in the shape of the plan: it presents decidedly more marked aspects of mechanical and distributive symmetries (compared to Biet Mediane-Alem) even if, obviously, it still presents negative features in the roof etc. Naturally, further investigations (that keep into consideration the actual fragmentation of the system) must clarify the real entity of the strain regime within the members, their level of dangerousness (as was stated in Margottiniâ&#x20AC;&#x2122;s 2006 report), and the quality and safety margin in checking the overturning movements. Another aspect, probably influencing the mechanical system that has originated, is connected to the release process of a co-active status that was created at the moment of the first digging work, phenomenon that can help to explain the spread of the vertical fracture systems.

53.4 Biet Abba-Libanos With the church of Abba-Libanos we have a totally different type of structure. The construction is located beneath a rock layer, from which the volume of the fabric was obtained and which is accessible from the south side (opening on a wide court). The building is therefore shadowed by

the bare rock that becomes its roof, while sideways the walls are carved and engraved and overlooks a sort of corridor that resembles the space of a cavern. The church is quite small with thick walls and presents evidently dangerous static conditions. Given the circumstance it is immediately possible to detect one of the main characters of the rock hewn system we are dealing with, and this is the fact that it is dug in the rock and thus obliged to inherit all the natural irregularities in the disposition of the rock layers. The vicinity with the walls of caves enables us to read, both on the walls of the building and on those of the cave, the strongly slanting direction of the surfaces separating the different tufa deposits. What characterizes the Abba-Libanos’ situation is the continuation of such dispositions with the same inclination in the ample volume of the rock overhanging the roof of the building. So the situation is the following: as long as the solidity of the rock layers is guaranteed, thanks to an inclination that is inferior to the internal friction angle or to an internal natural cohesion between different parts of the mass, the church’s members represent the resource for stability (in this case it might not even have to bear the entire weight of the overhanging rock). But when water infiltrates, as it has happened, this amplifies the existing discontinuities since it triggers chemical transformation phenomena that eventually cause relevant volumetric variations within the tufa-like blocks (described perfectly in Margottini’s report in 2006). The mass may then start sliding and weighing entirely on the construction. This fact has for some time exposed the fabric to a great thrusting action (as Margottini has rightly related this happens within the mechanisms of landslides) and the fracture pattern does nothing but enhance this phenomenon. Even if we only make a macroscopic interpretation of the imbalance, it is immediately clear that the overlapping of fractures denounces a motion of the upper voussoir of the mass that separates diagonally (from top to bottom) the lateral walls of the church (which have to resist the motion). The southern wall opening on the court is instead involved in an overturning action which highlights the cylindric hinge next to its base and the fracture pattern deriving from the engagement of the blocks it is separating into. The evolutions of the phenomenon are quite worrying because, on the basis of the frameworks surveyed in the past, it appears to be unstable. Angelini’s indicators clearly signal openings, but also new types of cracks can be noticed and particularly the escape from axial configuration of the pilaster drawn on the eastern lateral façade, of which the upper part has slided forwards. We still don’t know how fast the phenomenon is, but a monitoring action to try and capture its evolutionary process is undoubtedly urgent. Due to the complexity of the covering rock conformation (weighing totally around 2.500 tonnes) the entire diagnosis is very uncertain We do not know the speed of the phenomenon but it is absolutely urgent to monitor this process and assess the speed of its progress. The complex nature of the rock, which makes the roof (whose weight is near to 2.500 tonnes) and the numerous levels of discontinuity in the interior, make the entire diagnose highly uncertain. At this moment it appears not advisable to attempt to lean upon the surface of the rock, and at little distance from the rear wall of the cave, the reinforced cement props of that hold the temporary shelter. The pillars should be put at a greater distance from the cliff edge, but the space is not enough. 5.3.5 Biet Gabriel Rafael The monumental complex consists of two churches dedicated to the Archangels Gabriel and Raphael, which form a whole architectural complex. Outstanding and original in its features, it looks like the refurbishment of a pre-existing fortress-royal court (several pieces of evidence refer to a probable pre-Christian settlement), it is hewn out of a tufa ridge and inserted between two courtyards. The view on the larger and deeper court on the north side is characterized by a

great cliff crossed by a small wooden bridge from the only access road on the opposite hill. The courts are part of a sophisticated water collecting and control system provided with cisterns and outlets. The monumental complex faces north while the interior is oriented east west in a longitudinal succession of rooms (six in all). The structure that emerges from the excavation is articulated along two long external walls of different heights, on transversal reinforcement walls, and on a series of columns set centrally with certain regularity. The roofing, little more that two metres thick and nearly flat, is crossed by channels for draining water. The artefact is, so to speak, embedded and camouflaged in the rocky crest; it is an integral part of it and it maintains some of its asperities; others are smoothed down, but without alteration of the natural unevenness. The whole is characterized by a sharp sub-horizontal dividing line at the summit and is crossed, mainly on the south side (shallow court) by numerous cracks, the results of deterioration caused by continuous exposure to the sun, a consequence of this are the formation of brittle superficial crusts. The whole south face is characterized by rough chisel work that confers a rather primitive look to it. The reason for this escapes us since the quality of the rock promises considerable and widespread deterioration, with numerous unstable patches, vertical and transversal cracks, and finally, an intaglio work on a lesena which perhaps was interrupted by a sudden collapse, or by a mere second thought upon consideration the unstable nature of the rock. The inner space is obtained by creating a level ceiling reinforced by a network of beams connecting the central pillar to the walls. The thickness of the roof, albeit exceptional, it is not at the same level with the roofs of the other temples in the same monumental unit; although this will not prevent seismic damage, it also explains why there is no visible evidence of instability. We may try to synthesize the situation thus:

two considerable damaged areas cross the church from east to west; these mainly affect the levels of intrados and extrados of the ceiling, and to a lesser extent they also seem to affect the floors but this is the case only nearer the inner doors of the two transverse walls. such damaged areas also affect the adjacent vertical structures consisting of the three important transverse walls (the fourth outside to the west is bulky in design) and of the pillars; a concentration of damages also concerns all the inner walls facing south. a very worrying set of cracks interests all the ast cell at the end, the only one, save the central passage, with a threefold window looking onto the south court; damage is serious and in progress, indicating a subsidence movement independent from the local system.

The cross section described above illustrates relevant movements; let us take a closer look at them: 1. A vertical fracture crosses the whole body of the church east to west, nearly symmetrical with the longitudinal walls. 2. Another fracture, also vertical and parallel with the first penetrates near the south inner front splitting it from the rear wall of the rock (the coarse and little worked one, which at the top also rises above the floor level of the terrace) 3. This last fracture line increases becoming macroscopic beginning from the door giving onto the south court in an easterly direction: here, between the rear rock and the hewn body of the building there is a true discontinuity. This is easily visible on the small front of the building, separated by a fracture in the south rocky crest, inside the east chapel where we

observe incipient collapse and falls of material (for the priest's safety a small wooden ceiling, now collapsed, had been devised). 4. Two highly critical local situations reveal movements of subsidence still in progress; this occurs in particular in the architrave system above the passage to the south court and in the chapel described above, in which we detect a process of subsidence concerning the north east front which moves away from the rest of the building and, symmetrically, there is a crisis in the irregular wall, where the threefold window is, divided into several patches. It is not easy, at the present moment, to understand the causes of such dynamics without a monitoring system. We can state the following: - The imposing roofing structure is divided into two blocks; these cannot collapse by virtue of their very thickness, but it bears upon the upright structures, (the southern one no longer being in line with its original balance); the whole, albeit being a flat slab, behaves like a great broken architrave. - The uprights suffer from these movements: on the south side they are fractured in several places and, for their rotation, they probably bear upon some discontinuities in the rock as their pivots. - The general mechanics may be better understood on the transverse septa upon which the cracks of the rigid parts in subsidence appear (whereas on the external vertical walls phenomena of opening and closure of hinges are manifest) - The above said phenomena are a cause of concern, being connected with possible transversal movements not opposed by effective external impediments. It is very difficult to pinpoint a cause with any certainty; the two vertical levels of separation may be caused by pre-existing detachments inside the living rock or appeared during the works. An extension of the fracture lines on adjacent rocks (east) seems to back this hypothesis; It is true that the discontinuity on the south side is conspicuous, but it is hard to say that it was the root cause of the phenomenon. It is also apparent that the whole system is fragile: all it needs is a crack on the top to trigger a long process of deterioration first and of structural vulnerability thereon. The rock face on the south side is fragmented and altered in its physical-mechanic quality; it could still be a crucial factor in setting off the mechanism that destabilizes the east chapel. Here we are in the area of the building that has the least in the way of subsidence and rotation in a north-northeast direction. The shape of the artefact insures, in fact, a considerable rigidity on the north from, provided as it is by sturdy rock ledges, whereas what appear very week are the area around the entrance door on the south court and as already said, the walls of the chapel. Apparent sources of deterioration i.e. water percolation exist in the western rooms of the complex. The thickness of the roofing, great as it is, it isn't as great as in the other temples of the monumental complex; this does not exclude effects due to seismic activity, but it explains why we do not observe blatant effects of structural damage entirely due to this cause. The results of the sclerometric surveys sent, provide values lower to those reported in Margottini (it must be said on this point that the values obtained with the sclerometer regard surface hardness and, in our case, depend on the emergence of a surface hard crust, naturally produced by tufa rock) , whereas a certain variability in the reaction index and therefore of the present mechanical qualities of the rock (which vary according to position and exposure) is confirmed. Collating such results with a description of the static quality of the system may be carried out within the context of appropriate mechanical tests, and upon the base of hypotheses regarding basic mechanics in progress.

An obligatory path to follow in order to proceed with a minimum chance of success in the diagnosis process, consists therefore in monitoring some cross sections of the building: it is important to ascertain if and how movements occur and in which blocks. In so far as concerns defence works from the effects of atmospheric agents, it must be said that the church of Biet Gabriel-Rafael is particularly suitable, thanks to its flat roof, to experiment non invasive methods, which might be put into operation once the structural safety is established.

TAB. 5.I SYNTHESIS OF THE SYSTEMâ&#x20AC;&#x2122;S STATIC INTERPRETATION In a natural situation where the rocks are disseminated with discontinuities, present right from the beginning when the churches were first carved, during the centuries, especially because of the water infiltrations, the monolithic architecture structures have become thrusting. However, being structures that were originated as monolithic, the weight distribution can be very unfavourable in the new asset (for example the thickness of the roof is much wider than standard sizes in order to ensure protection from water). These structures undergo both pressure caused by the weight of the same structure (in some cases very consistent) and of seismic origins. ORIGIN

Natural

DESCRIPTION

AGENTS

Natural discontinuities of Water the rock

ACTION Water infiltrating through the oblique discontinuities, transforms the discontinuities into fractures creating separate blocks and encouraging sliding movements.

CONSEQUENCES The monolithic system transforms into a THRUSTING system, like a constructed architecture but with a totally anomalous load distribution

ACTIONS APPLIED TO TYPE OF FRACTURE THE SYSTEM VERTICAL â&#x20AC;&#x201C; OWN LOAD

HORIZONTAL SEISMIC

a. Damage associated with the opening of hinges in block-mechanisms (typical of arcs and vaults); they connect to the trend of the pressure curve of thrusting load systems b. Vertical damages (for the concentration of pressure like in pillars or walls)

Oblique damages corresponding to the corners, widening at the top

KINEMATIC MOTION AND TYPE OF GENERATED INSTABILITY

GRAPHIC REPRESENTATION

a. Attempt of outward rotation of the walls (out of plumb). Mechanisms for blocks (typical of arc or vault systems) b. Differential deformations between wall strips diversely affected by compression forces

Attempt of the walls to turn outwards. Rotation and partial detachment of the corners.

TAB 5.II BIET ABBA LIBANOS – Eastern Group Kinematic motions Description

TAB 5.III BIET GABRIEL RAFAEL – Eastern Group Kinematic motions Description

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BIET GABRIEL RAFAEL – Eastern Group Crack Pattern

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TAB 5.IV BIET MARIAM â&#x20AC;&#x201C; Northern Group â&#x20AC;&#x201C; Kinematic motions Description

In the section, we can see the impressiveness of the cover that, in case of seismic movements, creates dangerous ripple due to its weigh. The seismic origins of the fractures can be gathered from the shape of the same fractures that are narrow in the lowest part and wider in the upper part.

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TAB. 5.V BIET MEDHANE ALEM – Northern Group – Kinematic motions Description

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TAB. 5.VI BIET EMMANUEL â&#x20AC;&#x201C; Eastern Group The considerations made for the former churches count for Biet Emmanuel

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6. PREVIOUS RESTORATIONS There are no written records regarding the repair and restoration works carried out on the churches of Lalibela until those carried out by Architect Sandro Angelini from 1967 to 1970 on a mandate by the International Fund of Monuments and of the Ethiopian Committee for the Conservation and Restoration of the Lalibela Churches. However, from the oldest drawings and photographs available we can deduce that several repairs were carried out through the years. In 1882 Raffay represents Abba Libanos with a trench on the right of the façade and with the base of the church rebuilt with masonry. This testifies that, in time, problems regarding statics and conservation have evidently prompted repairs and restoration. Beginning from 1920 and up to 1958, various restoration works were carried out on the churches, of which, however, we have no account or written records. These were, in the main, haphazard interventions carried out sporadically, chiefly in an attempt to combat water percolation during the rainy season; at the time, repairs were made with mortar. There are only oral accounts and no written records describing restoration works carried out during this period. Several repairs were carried out in 1920 by a firm described as “Arab”, probably Egyptian. Such works were, at any rate, restricted to the sealing of fractures with lime mortar, and only concerned the churches of Biet Mariam, Biet Emmanuel, Biet Golgotha and Biet Danaghel. In 1958-59 an intervention, on behalf of the Ministry of Public Works by the Sebastiano Consoli enterprise, is recorded. Existing records are restricted to service orders signed by Surveyor Rosazza of the Ministry of Public Works, buy these do not include reports or accounts regarding the actual works carried out. Only in 1967 Architect Sandro Angelini collected a direct witness account from Consoli, the entrepreneur, and tried to reconstruct in more details the nature of the works carried out. (Angelini Archivi, doc. M1 CL 02; M1 CL 03, M1 CL 05 a,b e c; M1 CL 06 M1 CL 07 M1 CL 08). These regarded solely Biet Medhane Alem and Biet Emmanuel, and were highly invasive works of which we can see the mark in the holes and chisel work on the façade, made to fix nails and metal rods to anchor the cement mortar used. Here below, and in the description of the interventions regarding individual churches, I shall detail the works carried out by Sebastiano Consoli. 6.1 Sandro Angelini’s restoration work Only from 1967 to 1970 a comprehensive restoration programme of all churches was appropriately conceived and managed by the International Fund for Monuments and by the Ethiopian Committee for the Conservation and Restoration of the Lalibela Churches. The restoration was directed by Architect Sandro Angelini and, for the first time, the structural problem was also examined. In so far as concerns the restoration project, the philosophy adopted was aimed at bringing the churches back to their original state, first by removing previous restoration works. As Architect Angelini himself writes in his reports “…The guiding principle of this preservation effort is to safeguard the churches from further deterioration, remove false additions and to re-establish where aesthetically permitted the monolithic form and character that they once had.”. We must also stress that Angelini’s approach was at first holistic and analytical and that he presupposed a preliminary broad informative survey of all monuments.

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The intervention followed these phases:

Strengthening Protection Removal (of additions from previous restoration) Integration Restoration of Previous restoration works Restoration of low relieves Restoration of paintings Restoration of the interiors.

In general, Angelini made a detailed survey of the fractures and cracks in all churches, applying in many of them fissurometers of both metal and glass (gauges) for monitoring structural movements. Structural consolidation interventions were, unfortunately, not always adequate since a deeper comprehension of the causes of the cracks was lacking. As a consequence, concrete with a high power of adhesion and expansion (Embeco) was employed in the roof of Medhane Alem and in some of the churches metal harpoons imbedded in concrete were employed to fix parts which were in danger of falling, alas, not always such works were adequate for the type and nature of fractures. Great attention was paid to the search for a material capable of waterproofing both the roofs and the walls of the churches, which were seriously threatened by percolation of rainwater (products based on resins and fluorosilicates). Angeliniâ&#x20AC;&#x2122;s approach focused of the recovery, as much as it could be achieved, of the original state of the churches, as a consequence an enormous amount of work was done to remove the damaging restoration works done earlier. In almost all churches, cement crusts applied on the monolithic rock were removed, and in the case of Medhane Alem and Biet Emmanuel the layer of pitch and red paint applied by Consoli had to be removed; many structures and walls built in later time were demolished along with reconstructed parts of mouldings and plinths thus exposing the original stone blocks. Finally, a general thorough clean up of all superstructures and deposits accumulated over the years was accomplished. Besides his intervention on the churches, Angelini carried out an important archaeological excavation, and a clean up of trenches and drainage systems. In fact Angelini was perfectly convinced that the chief problem for the churches was generated by rainwater that falls in large amounts within a very short time during the rainy season. The restoration of the complex drainage system was therefore held to be of paramount importance for the control and management of rainwater. Several types of excavation were carried out: A dig aimed at clearing debris out of known and open trenches, churches inner rooms and surrounding courts. Excavation and cleaning up of the upper perimeters in order to prevent the refilling of trenches and courts by rushing flood water, and restoration the rocky border of excavated works. This particular excavation exposed numerous trenches and tombs hewn in the rock, as well as traces of the hut villages which pre date the building of the churches. Excavations, which uncovered great trenches, now lost because completely filled up by soil and obliterated by debris. Cleaning up the Ghiorghis River where extraordinary water control works were discovered which consisted of chiselled walls and of a system of pools and tanks designed to slow down the speed and to store water. The cleaning up of

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the Jordan river led to the discovery of the important system which, from the Monolithic Cross, drains the waters. Works undertaken by Architect Angelini took place in two campaigns lasting 4 months each, the first from January to May 1967 and the second from the 4th of December to the 27th of April 1967, and one lasting 3 months from the 16th of February to the 16th of May 1970, when works were quite suddenly halted. (See letter in Angelini’s Archives, RD to JG 30.03.70.) 6.2 Restoration interventions on individual churches 6.2.1 Biet Medhane Alem The intervention of Sebastiano Consoli for the Italian Ministry of Public Works and the Local Authorities, intended to be an articulated and comprehensive one on the church. Generally speaking the majority of the great monolithic pillars of the façade were rebuilt of masonry with squared stones. The under gutter pediment moulding was almost entirely rebuilt. A clear testimony to this intervention derives from a comparison between Raffray’s drawing of 1882 and later photographs. We must however stress that in 1939/40 after his visit to Lalibela, Luigi Bianchi Barrivera reported that the church of Medhane Alem was in poor state of conservation and that some pillars had been rebuilt with tufa to support the pediment moulding. (SIC) Patches of concrete made on the façade involved the insertion of numerous iron rods to hold such plastering work. North Façade: With the exception of those of the NE wall corner, all pillars were reduced to about half their original height and then rebuilt with squared stones. Even the moulding, partly missing, was rebuilt of reinforced concrete. The third window from the East in the first order has been completely remade. Many of the monkeys heads of the windows were restored in their place and several patches of the façade were plastered up with mortar. At the time of the Consoli intervention the access staircase to the door had already been restored. East Façade: Not many interventions here, save for the thickening of the bases of the third and fourth pillar in an attempt to combat a serious deterioration of the rock. Several patches of plastering on the façade and at the level of the moulding, was in a good state of repair. South Façade: Also in this case all pillars, with the exception of the corner ones, were found reduced to about half their height and were therefore rebuilt with the same procedure of those of the North façade. The façade itself resulted, on the contrary, intact and was only patched up with plastering in some points. Two stone steps were placed at the door whereas a third step of concrete turned out to be there as part of an earlier restoration. West Façade: The third pillar was cut by half, and so was the third from the South, which appeared seriously deteriorated and rebuilt like all others with stone “bolognini”. The façade had not been touched in its base, whereas at the top small cement repair were made. Here too the doorsteps date back to an earlier restoration.

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All façades were coated with red paint in an attempt to waterproof them. Two coats of paint were laid at a year’s distance from one another. A third coat was planned but never applied since the works were discontinued. From oral accounts collected by Angelini, the ingredients of the paint were as follows: I coat: Podomy black with a bitumen base II coat: Podolic red III coat: Podobes red (not applied) Roofing: At the time of the Consoli intervention the roof appeared to have been patched up in several places, and this suggests that the cracking up had started a long time back. Consoli poured concrete and planted iron rods in the rock in order to harness his coating to it. The red paint already used on the façade was to be used on the roof too, but this did not happen thanks to the interruption of the works. Consoli carried out no intervention inside the church. Angelini’s intervention on Biet Medhane Alem required first the complete removal of previous restoration works, and in particular a iron sheet roofing protection, then all cement crusts of the roof were chiselled off exposing the original rock surface with its structure of sculptured arches. Also removed were renewed parts of the moulding and all the layer of pitch and red paint applied by Consoli were scraped off . All recent internal partition walls were removed both in the church and in the Sancta Sanctorum. Observations on statics made by Engineer Dell’Acqua had already highlighted the tendency to opening up processes on the corners with hinges low down. “In substance the church appears to be splitting while remaining firm on its foot and opening up like a flower at the top”. In an attempt to halt this movement two iron chains were fixed transverse to the plan of the church in the Sancta Sanctorum, and two more chains across the inner wall edges next to the first cell. Unfortunately this intervention was not sufficient to halt the outward movement of the church’s walls and corners that are still moving as demonstrated by gauges placed on the roof by Angelini himself which show a split up to 1 cm wide. 6.2.2 Biet Emmanuel In 1920, some fractures were filled up by Consoli, as in the case of Beit Medhane Alem all façades of the church were plastered with cement, then lined with bitumen and finally with red paint. The skirting was redone and the threshold of the entrance doors was chiselled in order to lower its original level. On the floor some holes made to anchor scaffolding are visible. The application of cement mortar on the façades, on the skirting and plinths required the piercing of numerous holes in the rock for the insertion of iron rods and nails to harness the plastering cement. All the perimeter plinth, which appeared highly eroded, had been completely remade of concrete. On all façades were three coats of red paint intended to waterproof them. East Façade: Remake of the first and second façades in concrete. The South East corner above the first band is remade in squared and fashioned stone. Remake of almost all windows of the second order with stone dowels.

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South Façade From the first band to the guttering moulding almost entirely remade. Remake of the skirting and plinths as above. West Façade: Beyond the remake of the skirting and plinths in concrete, the South West corner and part of the upper façade of squared stones, were remade. North Façade: The upper parts are mended with cement and squared stones. Complete remake of the gutter. Replacement of various monkeys heads on windows. Roofing No intervention. Always in 1958/59 a temporary roof was built to protect Medhane Alem and Biet Emmanuel Angelini intervened in the first place with a chiselling off of all the pitch and red paint coating applied earlier by Consoli, and also with the reopening of the underground passage connecting Biet Emmanuel with Biet Mercurios. 6.2.3 Biet Mariam Before Angelini’s intervention it appears that the wide cracks crossing the roof had been filled with a mixture that did not help to prevent water infiltrations into the interior. The date and the ways of this restoration are unknown. The first phase required here too the demolition of previous works both outside and inside, and the base around the perimeter and corners were restored with one single concrete layer, mixed with local ground red stone. To deal with statics, metal straps were inserted into the North and West porches with the aim of anchoring them to the church since they presented a tendency to become detached from the monolith. The church presented at the time strong erosion in the lower parts of the façades and lateral porches. Angelini intervened therefore consolidating the eroded parts and completely remade the guttering moulding with a sole concrete layer then chiselled. Cracks present in the porches were sealed and consolidated by inhibition with Akemi and Embeco. 6.2.4 Abba Libanos In 1920 a concrete plastering coat was applied to the main façade and the base of the walls were mended along with the North West wall edge that evidently had collapsed. In 1958 (?) a temporary roof was installed to keep the rain off. With Angelini first of all part of the wall plastering of the façade was torn down in order to assess its real consistency. Already in Angelini’s times the church presented serious statics and structural problems, on this point it is interesting to look at the work, begun and unfortunately abruptly terminated due to the halting of the works in 1970, of cleaning up and exposure of the mother rock with the aim of relieving the roofing from excessive weight. The statics survey carried out by Engineer Dell’Acqua stated clearly, in fact, that: “….given the heavy weight bearing upon the Temple, represented by the might of a boulder of rock 10 metres high, we believe that the same boulder be about to detach itself from the hill and definitely come to bear upon the Temple, whereas perhaps in the past it was coming to bear upon the same hill.” (Angelini Archive – BG Doc. M 1 CM-02)

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The problem described by Ingegnere Dell’Acqua persists today with the aggravating addition of the shelter above the rock shelter that threatens further a situation already long deteriorated and seriously dangerous. 6.2.5 Biet Gabriel Rafael Interventions on this church have been very much restricted and limited to some repairs to fractures present on the roof and on the walls, consisting of filling up with mixtures of mortar and concrete. In a first phase, of which we don’t know the the date or the author, numerous patches of lime were at the level of the roofing, evidently in an attempt to contrast the leaking of water, which still remain today. As it has emerged from the analysis carried out, such cracks are of a structural nature and the problem of leaking cannot be easily solved with simple operations of patching up the roofing or filling up cracks. Not even Angelini came in with a rational approach on this church, due to the halting of works, and for this same reason we do not have a complete survey but only general ground plan of the site. With Angelini’s intervention all plastering and wall repairs on the façades were torn down, as well as those on the roofing and in the interior; a moulding of the late period was also removed. The walls of the East cells were also consolidated with cement. The cleaning work of the roofing was aimed at discovering the cracks and then at sealing them with a product which in Angelini’s view provided greater security of hold. Such crack sealing operation aimed at protecting the churches from water infiltration was carried out on the other churches (Biet Mariam, Medhane Alem, Biet Golgotha, Biet Emmanuel, Biet Maskal, Biet Danaghel) and consisted in the application of sealing thermoplastic stucco Lactivoplast or with a sealing mastix of polyurethane resin. Later the cracks were sealed with Embeco cement and then with a “caldana” of concrete made of white and black cement mixed with gravel obtained by crushing the red tufa of Lalibela.

6.3 Interventions after Angelini’s restorations For the following years, apart from the usual punctual operations carried out upon request from the clergy, and the cleaning up of the courts, we have no record of significant interventions. In 1974, the Centre for Research and Conservation of Cultural Heritage (CRCCH) was created. Between 1974 and 1982 a project by the UNDP, UNESCO and CRCCH was carried out for the Ethiopian Government, aimed at the preservation and promotion of various Ethiopian historical sites, including Lalibela. Biet Emmanuel was subject to piezo-metric surveys and 4 hygrometers were installed in the churches in order to test temperatures and humidity levels. In April 1978 a 4-day Symposium was held concerning stone conservation, in cooperation with ICCROM. From this event an international panel of experts emerged which tried to identify the main problems concerning the conservation of the churches, and it carried out several laboratory tests. The panel issued the following recommendations that should be observed before undertaking any future restoration:

The need to carry out analytical surveys of a physical-chemical, mechanical, geological, climatic nature. The need to carry out biological inspections.

Still in 1978 the site of Lalibela was inscribed in the World Heritage List.

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In 1982/83 the World Heritage Fund financed the photogrammetry survey of the churches. The mission also contemplated the formation of local specialized personnel. In 1986 Biet Mariam was protected with temporary roof and in 1993 the same was done for Biet Emmanuel. In 2007 the European Commission financed a project consisting in the erection of 4 roofs to cover 5 more churches: Biet Mariam/Biet Maskal, Biet Medhane Alem, Biet Emmanuel, Biet Abba Libanos. Today this project is nearly complete. Concerning the judgement on the shelters, the entire team of experts confirms the statement on the same problem previously expressed in Pietro Laureanoâ&#x20AC;&#x2122;s report in 1997 (view annex for the abstract of the report). Now that the shelters have been constructed it is necessary to make the following considerations: 1. The shelters have been modified in respect of the requests made by UNESCO compared with the original project. This originally included the insertion of poles in the rock and digging deep ditches to fix the tension rods. The poles would have had an even greater visual impact than the actual ones and the bases would have meant an invasive intervention in a historically and archeologically relevant site. 2. However, the shelters that were realized do have a strong visual impact that surmounts the site. 3. The pillars are set on plinths made of cement and steel that are only resting on the rock, but they do however have a strong visual impact and they are set within the courtyards that were dug beneath ground level and in many cases they are right next to the faĂ§ades of the monolithical churches. 4. Although the shelters are removable, it is not easy to disassemble them. The operation needs highly qualified workers and means rebuilding heavy scaffolding. What this really means has to call back the people who set them up. The disassembling operation is expensive and dangerous, as much as the building operation was, if not more. 5. Being as the shelters were realized especially for this site, they will hardly be reusable in other situations. 6. On the basis of cautious considerations made without specific knowledge on the structures, we can affirm that the shelters seem to be solid but the reticular structure that was chosen makes them vulnerable to any small mistake in setting them up or to the collapse of even only one of their junction points. The deterioration effects of weathering and birds guano on the plastic shields are not known. Certainly the visual aspect, now an immaculate white colour, will no doubt worsen considerably. 7. For the consideration of the two previous points we have reasons to think that a periodical very expensive maintenance will be necessary. 8. The shelters are horizontal so they do not solve the problem represented by rain that, carried by the wind, does not fall vertically and will hit the churches from the sides.

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9. The shelters will create a new microclima beneath them, constituting a wonderful refuge for birds that will leave their corrosive guano.

In the case of Abba Libanos we stated that the shelter with the two pillars resting on the hypogean chamber and the terrible structural conditions of the church, might cause serious damage. The drainpipes are placed in a wrong position and water can cause serious dangers at the monuments.

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Realization of the shelters

Shelter on Biet Mariam and Medhane Alem

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Shelter on Abba Libanos

Particular of drainage system of the shelters

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Particular of drainage system of the shelters

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Drainage System in Biet Miriam

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Consequences of drainage system in Biet Miriam

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LINES FOR AN ARTICULATED INTERVENTION OF RESTORATION

An specific assessment of the statics of the churches of Lalibela its necessary because every artefact represents an unicum, since unique and singular are, in each case, the position within the rock stratum, the orientation and inclination, the discontinuities crossing the succession of strata, the forms and variants in the distribution of masses and spaces. From this point of view a structural approach demands specific analytical strategies, of interpretation of fissure patterns, formulation of hypotheses regarding the causes of decay and upset. Upon the acquired clinical information concerning each building we may then work out strategies of consolidation and for securing systems. As said above, in many cases the evolution of mechanisms and an understanding of their state, the degree of risk, may depend upon readings and specific observations on the speed of movements, and most of all, establishing a possible hierarchy for them. The masses at play in the system of rock churches at Lalibela are considerable (and “disproportionate” on account of their genesis, with respect to building made of blocks), therefore great importance is given to the exact positioning and dimension of seismicgeological problems. The first interventions of Architect Angelini have been carried out with great wisdom, but are obviously sporadic and limited (even if it would have been important to continue the reading of the numerous markers positioned on the monuments). A perspective of consolidation, calibrated case by case (with some illustrious exception where questions are chiefly of a geotechnical nature, this is to say involving serious movements of the ground, as in the case of Abba Libanos) may adopt methods and technologies now fully acquired by the scientific community. We go from the insertion of metal harnesses (when the movement to be contrasted is clearly known) to the regeneration of mechanical qualities for a material which may have partly or entirely lost them, to systems of harnessing to the ground (by means of posts), to all the spectrum of fiberstrengthening compounds, which may confer surprisingly good mechanical qualities to structural systems (with an eye, of course, to concealing their presence by plastering over). It goes without saying that consolidation operations could not be separate from an equally urgent preoccupation for the protection from atmospheric agents and from a check out of the water which have hitherto represented the most obnoxious destabilizing factor.

7.1 The Pilot Yard and waterproofing The realization of a pilot construction yard for conservation is the key factor for starting a restoration experience which can be managed locally and which can develop into durable maintenance and conservation. The waterproofing operation has been chosen as the first step for the experience because water seepage is locally considered one of the worst deteriorating factors and that is why the shelters were built. The operation intends to demonstrate that it is possible to achieve a good level of waterproofing using mortar and local labour, implementing non-invasive and reversible forms of intervention on the monuments. The structure that must be chosen for the site must have the following characteristics: • Represent all the main structural rock hewn typologies present; • Undergo serious structural deterioration phenomena thus representing an emblematic case; • Undergo serious rain-water seepage; • Have an easily accessible semi-flat roof without relevant ornamental elements

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We regard the architecture of the twin churches of Biet Gabriel-Rafael as the most suitable both for an exemplary research on pathologies and for experimenting the pilot waterproofing project. In fact the churches have the following characteristics: •

They present different types of problems, both from the conservative and from the environmental restoration point of view. The structure is the result of the overlapping of actions that in time have lead to a transformation of the typology from hypogeum to monolithic architecture. A relevant feature is that it is still closely connected to a system of hypogean courtyards, draining tunnels and cisterns for gathering water;

•

it presents a significant fractured situation and needs several different types of intervention but is not in such a state to determine immediate risk for the entire structure. Operations on the church can illustrate the different restoration techniques;

•

it has serious water seepage problems as a result of structural failures and detachment of materials that justify the urgent need for waterproofing;

•

It has easily accessible semi-flat roofs, without relevant ornamental elements, that have already undergone several repairs with mortars and cementing substances. Therefore the materials have lost their originality.

Despite the structural problems that are being analysed, at a first assessment we can say that the church of Biet Gabriel-Rafael is particularly suitable for a waterproofing intervention with noninvasive methodologies, precisely for its exceptionally flat roof. Obviously this intervention will be possible only once the problems relative to the structural security have been analysed. 7.2 Integrated operational strategy The analyses of Lalibela as an ecosystem enabled a better focus on the issues and on the operational integrated strategy that can be summarised as follows: 1. The site of Lalibela constitutes a complex system of which the churches represent the most important and known aspect, but they are only a part of the astoundingly interesting overall urban and territorial design that is still intact; 2. The linear systems of the space organization, especially the incredible trenches and channels layout in open air and underground, are an integrating part of the overall design; 3. These systems are partially dug and partially obliterated, but, with the exception of some cuts created by the modern road, they are mainly intact; 4. The complex of traditional houses is still intact and very interesting and it gives the site a unique charm in that it represents an extraordinary example of archaic architecture in the historical city; 5. The reconstruction of the overall territorial framework, the participation of the institutions and of the local actors to the project and the involvement of the inhabitants guarantee for the complete valorisation of the site and maintenance in the long run. To protect these values it is necessary to integrate the safeguard actions on several levels: 1. Monumental: carrying out the restoration of the churches; 2. Environmental: recovering the trenches, the water managing systems, the tunnels, the underground channels, the soil protection and the safeguard of the ecosystem;

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3. Urban: through the visualization and valorisation of the entire historical city with its paths, doors, inhabited areas and civil spaces; 4. Social and town management: safeguarding the traditional habitat through the restoration and the functional adaptation relative especially to hydraulic and sanitary services, to guarantee incentives to the population and the inclination towards architectural maintenance. For all these actions the cognitive aspect and the overall coordination of the activities are fundamental. The pilot actions, cleaning operations, monitoring, mortar and other material tests and local training are integral parts of the cognitive aspect because a restoration project cannot be carried out without concrete testing on the monuments and pilot experiences or without the assessment of the local capability to guarantee the operation and the subsequent maintenance.

7.3 Monument restoration strategy Concerning the restoration of the monuments until now the following activities have been carried out: 1. Geometrical knowledge of the fractural frame and analysis of disorder phenomena 2. Diagnosis on structural vulnerability for the most endangered monuments 3. Identification of the Biet Gabriel Rafael complex as the pilot site for the restoration action 4. Identification of the mortars for the pilot action in waterproofing 5. Start of the experimental project in waterproofing and training of local workers.

DIAGNOSIS

The monument restoration must follow the general programme, which can only be implemented if the cognitive researches are produced (survey, history, typology). 1. Structural lecture a) Geometrical knowledge b) Fractural frame and analysis of disorder phenomena c) Diagnosis on structural vulnerability d) Monitoring of monument e) Statical calculations f) Assessment of seismic risk g) Physical and mechanical analyses of materials 2. Analysis of the architecture and valuable elements 3. Analysis deterioration factors on surfaces and materials 4. Diagnosis formulation assessment of comprehensive factors of risk and assessment of securing degrees.

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MANAGEMENT

RESTORATION

1. Analyses of intervention typologies in relation to: a) Security degree b) Invasiveness; c) Harmony, aesthetic and environmental compatibility d) Reversibility; e) Local sustainability 2. Restoration project of the monument Securing of structures Decor elements, plants and surfaces 3. Environmental restoration of the monument context a) Drainage restoration b) Management of structures and visitors

1. Assessment of local sustainability 2. Indicators for safeguarding the values and for the achievement of the management objectives 3. Management and maintenance project 4. Organization of tenders

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