ARCHAEOMETRY OF A NEW PUNICO-TURDETANO AMPHORA TYPE: THE OIL AMPHORAE FROM THE CAMPIÑA GADITANA (CADIZ, SPAIN) P. A. Carretero1, A. M. Arruda1, M. T. Carretero2, M.D. Petit Dominguez3, R. García Gimenez4 and M.I. Rucandio5 1
Centro de Arqueologia, Universidade de Lisboa, Portugal, pacarretero@gmail.com Universidad Complutense de Madrid. 28040- Madrid. Spain 3 Departamento de Quimica Analitica y Analisis Instrumental. Facultad de Ciencias. Universidad Autonoma de Madrid. -28949-Madrid. Spain, mdolores.petit@uam.es 4 Departamento de Geologia y Geoquimica. Facultad de Ciencias. Universidad Autonoma de Madrid. 28949-Madrid. Spain, rosario.garcia@uam.es 5 CIEMAT. Avda. de la Complutense, 22. -28040- Madrid. Spain, isabel.rucandio@ciemat.es 2
Introduction Nowadays, the so-called Tiñosa amphora type was made between the 4th and 3rd BC centuries in the area known as Campiña Gaditana (Cádiz, Spain) for the púnico-turdetano civilizations that dwelled in it in that period (Carretero, Garcia & Feliu 2004). The name given to this amphora type comes from the first systematization after numerous documented units (Belén & Fernández-Miranda 1978) in the La Tiñosa site (Lepe, Huelva, Spain), although it was used for the first time in the typological classification of the Phoenician, Punic and Turdetana amphorae of the Iberian Peninsula by A. Rodero (Rodero 1991). Amphorae were containers widely used for storing and transporting liquid and semi-liquid merchandise such as wine, oil, salted fish, honey, etc or linked to religious rituals (Carretero 2006, Petit-Dominguez, Garcia-Gimenez & Rucandio 2003). These receptacles have been found in numerous archaeological sites discovered throughout the Mediterranean coast, most of them in marine underwater environments, since maritime transport was one of the main ways of establishing commercial ties between geographically separated regions. In this sense, the Gaditana area (Cadiz, Spain) (see Figure 1) was rich in different types of amphorae, since it was focused on agricultural and livestock exploitations, mainly vine and olive tree as distinguished farming, in the inside zone (Campiña Gaditana), and it also had a famous flourishing salted fish industry in the coast (Bahia Gaditana).
FIGURE 1. Location map and dispersion of Tiñosa amphora type
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A detailed study of Tiñosa amphora type made by Carretero (Carretero 2004) has allowed knowing that these containers transported top-quality olive oil between the Iberian Peninsula and Morocco, since it was one of the products more estimated of that period. The 4th century was a time with an olive tree intensive exploitation from the Campiña Gaditana to Sevilla. Olive oil was also essential for preparing perfumes in any kind of religious rituals. As example of religious centers, where this substance was used, were Castro Marin (Portugal) and funeral wells of Cadiz. The consumption of these products was abundant in all these aforementioned places. A more detailed study of these containers could reveal interesting data concerning aspects such as raw material origin, manufacturing process, use, etc. The traditional method for classifying amphorae was largely archaeological and typological. In the last decades, scientists began to use physicochemical information together with chemometric studies as a way of relating the composition of the ceramic materials of these amphorae to the nature of the raw materials employed, to technological aspects of amphora manufacture and to foodstuffs stored or transported in them (Petit-Dominguez & Martinez-Maganto 2000, Vigil de la Villa, GarciaGimenez, Petit-Dominguez & Rucandio 2003). In this paper, a chemical, mineralogical and physical characterization of Tiñosa amphorae was made. Analyzed samples came from different locations of Cadiz (Spain) and Castro Marin (Portugal). Results of these analyses were compared with those obtained from amphorae of the same area but of the Roman period. Owing to the large number of chemical and mineralogical results, several multivariate statistical studies were additionally performed in order to obtain relations among amphorae with similar characteristics and to establish significant differences among them, that might help to shed more light on the manufacture technology and to support certain archaeological hypothesis, such as to ascribe the making of these amphorae to a concrete area where the kilns, in which they were made, have not appeared yet. Experimental Description of the samples Figure 2 shows a Tiñosa amphorae type. It was a container with a straight lip, with the thickened edge towards the inside, without a neck and with a groove to the outside next to the edge. It was about 1 cm of width. The body of these amphorae was biconic, with light grooves that were horizontal as the inside as the outside parts. The back was pointed and the handles usually had an elliptical section, and it was in the shape of an ear and a little more than a half and a circle profile. The measurements of these completed and documented unit were around 110-120 cm high, with a 30 cm of diameter as maximum in the belly, and in the rim the diameter was around 1215 cm (it changes according to the productions). The inside of the amphorae was not covered with any kinds of resin because resin spoils the olive oil quality.
FIGURE 2. Tiñosa Amphora type
A total of 57 samples were analysed. From them, 37 samples corresponded to several locations of the Spanish province of Cadiz (13 from the Cadiz capital, 15 from Jerez de la Frontera, 1 from Espera, 2 from Puerto de Santa Maria and 6 of them were Roman dolia from Los Prados de Montegil), 19 corresponded to Castro Marin (Portugal) an the other one to Altea (Alicante, Spain). All of them were Tiñosa amphora type, except three Maña Pascual amphora
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type samples (one from Jerez de la Frontera and two from Cadiz) and another one from doubtful origin. Samples for the corresponding analyses were obtained by taking a minimum part of the archaeological object, with the aid of a scalpel with diamond tip, to minimize any damage and contamination. These samples were ground in an agate mortar and pestle in order to reduce the particle size and to secure homogeneity. Physicochemical Analyses Flame atomic absorption spectroscopy (FAAS), using a Perkin-Elmer 503 spectrometer, was employed for determining several major and minor elements, including Al, Ca, Cr, Fe, Mg, Mn and Ti. K and Na were measured using the same instrument in flame emission mode. Silica content was deduced by difference. The previous sample dissolution was carried out in the following way: a minimum amount of sample was treated with hydrofluoric acid in an open vessel and heated on a hot plate. It was followed by addition of aqua regia, heating again until dryness. The residue was dissolved with 1ml of concentrated hydrochloric acid and diluted with water to the mark in Teflon volumetric flasks. Care was taken to keep the contamination to a minimum. Ultrapure water was used throughout and all reagents used were of analytical grade. In all flame and emission spectroscopy determinations, blanks of reactive were analyzed giving signals under the detection limits. The mineral composition of the samples was determined by X-ray diffraction spectrometry (XRD), with the powder method by using a Siemens D-5000 diffractometer and working with CuKα radiation and Ni filter. Applied voltage and anodic current were 40 kV and 20 mA, respectively. Statistical study of chemical and mineralogical parameters A statistical processing of the data was carried out using the Stratgraphics Plus program, version 5.0 for Windows®. Correlation and multivariate statistical analyses were performed by using chemical and mineralogical data of the 57 studied samples. The variables were grouped in two different studies: (i) 10 corresponding to chemical data (SiO2, Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, TiO2, and Cr), (ii) 9 variables corresponding to data of total mineralogical composition (calcite, quartz, dolomite, calcium feldspars, potassium feldspars, phyllosilicates, pyroxene, hematite and amphiboles). Supervised Pattern Recognition was applied in this study. Linear Discriminant Analysis was used for hard classification purposes, trying to establish possible connections among groups of samples and variables (Marini, Magri, Baliestrieri, Fabrietti & Marini (2004); Garcia-Gimenez, Vigil de la Villa, Recio de la Rosa, PetitDominguez & Rucandio (2005)). This procedure is useful for classifying amphora dataset into groups according to the places where the samples were found. It generates a small number of functions of quantitative measurements which are linear combinations of the standardized pattern variables with weight coefficients. These functions are called Canonical Discriminant Functions and help to discriminate among groups of amphora samples with different origin. The procedure assumes that the variables are drawn from population with multivariate normal distributions and that variables have equal variances. Results and discussion Chemical analysis Major constituents, such as Si, Al, Ca, Fe, K, Mg, Mn, Na and Ti, were determined in the samples and the results calculated as percentage of their respective oxides. The content Cr as minor elements was also obtained and expressed the results in µg g-1 and was present only in some samples of Jerez de la Frontera and Cadiz with values between 23 and 120 µg g-1. A Supervised Patterns Recognition Study was applied to all chemical results obtained for the 57 samples. Linear Discriminant Analysis was designed to develop a set of discriminating functions which can help to classify samples and to extract all those amphorae with significant
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differences in chemical composition. 57 cases were applied to this study and 10 predictor variables were entered: 9 major constituents (SiO2, Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O and TiO2) and 1 minor or trace element (Cr). Figure 3A is a graphical representation of the samples as a function of the two Discriminant Functions. F1 represents 44.9 % of the total variance, where the most important standardized coefficients are: -0.692 for Al2O3 (in the negative part of the function), 0.753 and 0.693 for MgO and CaO respectively (in the positive part of the function). F2 represents 39.1% of the total variance and of particular interest are the standardized coefficients: -1.096 for SiO2 and -0.730 for Na2O (in the negative part). These functions with P-values less than 0.05 are statistically significant at 95% confidence level. As can be observed, major and trace elements are well separated for populations from Puerto de Santa MarĂa and Montegil (Roman Dolia). In the others there are overlapping, above all between the Jerez samples and those of CĂĄdiz. It can be also observed that sample of Altea is included in Jerez population. Those of Castro Marim amphorae show great dispersion but are distinguished because they are sited in the negative values of F2.
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FIGURE 3. Plots of Discriminant Functions. A. Chemical Data. B. Mineralogical Data. Mineralogical analysis The mineralogical characterization of the samples was made by XRD. The results deduced for each compound are represented in a Box & Whisker Plot (Figure 4). In this plot, each box encloses the middle 50%, where the median is represented as a horizontal line inside the box. Vertical lines extended from each end of the box (called whiskers) enclose data within 1.5 interquartile ranges. Values falling beyond whiskers, but within three interquartile ranges (suspect outliers), are plotted as individuals points. Far outside points (outliers) are distinguished by cruises (+). It was very interesting to detect the presence of amphibole and pyroxene, minerals associated to volcanic rocks, only in samples from the province of Cadiz. The presence of volcanic areas is nowadays well documented in different zones of the south of the Iberian Peninsula (Alboran Sea and Baetic Mountains). These volcanic materials were frequently added to ceramic pastes in order to decrease the plasticity of the pastes during the firing process avoiding cracks (Garcia-Gimenez, Vigil de la Villa, Petit-Dominguez & Rucandio (2006)) and they are evidences of the presumable local manufacture of these ceramic pieces. There were also high values for dolomite in dolium samples from Montegil.
FIGURE 4. Box and Whisker Plot for the mineral components
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For the mineral elements a Supervised Patterns Recognition Study was also applied to all results obtained for the 57 samples and 9 variables as was mentioned in the Experimental Section (Figure 3B). In this case, F1 represents 64.1% of the total variance, where the most important standardized coefficients are:-0.999 for phyllosilicates, -0.997 for quartz, -0.847 for calcium and sodium feldspars (in the negative part of the function), and 0.590 for dolomite in the positive part of the function. F2 represents 16.6% of the total variance and of particular interest are the following standardized coefficients: -3.463 for phyllosilicates, -3.271 for calcium and sodium feldspars and -3.197 for quartz (in the negative part). These functions with P-values less than 0.05 are statistically significant at 95% confidence level. From the study of the plot can be said that the most differentiated samples are those of Montegil (Roman Dolia) and the most dispersed are those of Jerez. Also there are well defined those of Castro Marim and those of Cadiz (includes the T-50 and T-51 of Puerto de Santa María and T-28 of Espera). The unique sample of Altea can correspond with populations of Cádiz, Jerez and Castro Marim, or well of other site, since there are no significant mineralogical differences. Also it can be deduced that the Mañá Pascual A4 (T-12, T-20, T-22 and T-24 and the doubtful T-26) are perfectly integrated in those of Cadiz and it can not be distinguished from a mineralogical point of view. Conclusions A suitable combination of the physicochemical and chemometric analytical techniques used for studying ceramic amphorae provides useful information and helps to shed more light on the nature of the raw materials used in the manufacture of the pieces and their possible origin, providing arguments to predict and to confirm archaeological hypothesis. In this sense, physicochemical and chemometric analyses showed a clear difference among samples corresponding to the province of Cadiz (Spain) and Castro Marin (Portugal), as well as there was a evident difference between the Roman Dolia amphorae from Montegil and the rest of Tiñosa amphorae. Even sometimes it was possible to differentiate among different locations inside the province of Cadiz, probably due to the existence of different production centers. For example, in the plot of the discriminant functions for the chemical data, it was possible to differentiate the Puerto de Santa Maria samples from the rest. And in the plot of the discriminant functions for the mineralogical data most of the samples from Jerez de la Frontera and Cadiz could be differenced. Bibliography Belen M & M Fernández-Miranda (1978): La Tiñosa (Lepe, Huelva), Huelva Arqueológica 4, 197-287. Carretero Poblete, PA (2004): Las anforas tipo “Tiñosa” y la explotacion agricola de la Campiña Gaditana entre los siglos V y III a.C.: Doctoral Disertation. Universidad Complutense de Madrid. Carretero PA, R Garcia & MD Feliu (2004): Anforas tipo “Tiñosa”: analisis de su caracterizacion quimico-mineralogica y su perspectiva historica. Avances en Arqueometria 2003, Servicio de publicaciones Universidad de Cádiz, 183-198. Carretero Poblete PA (2006): El aceite de oliva en los rituales de época púnico-turdetana: Castro Marim y sus paralelos Peninsulares, XELB 6, Silves. Garcia-Gimenez R, R Vigil de la Villa, P Recio de la Rosa, MD Petit-Dominguez & MI Rucandio (2005): Analytical and multivariate study of Roman age architectural terracotta from notheast of Spain, Talanta, 65, 861-868. Garcia-Gimenez R, R Vigil de la Villa, MD Petit-Dominguez & MI Rucandio (2006): Application of chemical, physical and chemometric analytical techniques to the study of ancient ceramic oil lamps, Talanta, 68, 1236-1246. Marini, F, AL Magri, F Baliestrieri, F Fabrietti & D Marini (2004): Supervised pattern recognition applied to he discrimination of the floral origin of six types of Italian honey samples, Analytica Chimica Acta, 515, 117-125.
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Petit-Dominguez MD & J. Martinez-Maganto (2000): MCD fast derivatization procedure for the identification of resinous deposit components from the inner wals of Roman age amphorae by GC-MS, Talanta, 51, 727-734. Petit-Dominguez MD, R Garcia-Gimenez & MI Rucandio (2003): Chemical characterization of Iberian amphorae and tannin determination as indicative of amphora contents, Microchimica Acta, 141, 63-68. Vigil de la Villa R, R Garcia-Gimenez, MD Petit-Dominguez & MI Rucandio (2003): Physicochemical and chemometric characterization of late Roman amphorae from the Straits of Gibraltar, Microchimica Acta, 142, 115-122. Rodero A (1991): Las รกnforas del Mediterrรกneo Occidental en Andalucia, Trabajos de Prehistoria 48, 275-298.
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