Lurgan Geology Trail

“Roots dig deep Landscape inherent Words from stone Dirt we inherit.”

‘Inheritance’ by Mark Cooper.

Woolly Mammoth

Ammonite

Age

Clay and lignite Rhyolite Basalt Chalk Mudstone Sandstone Sandstone (not shown on map) Limestone (not shown on map) Greywacke and mudstone Greywacke and mudstone

4. Volcanoes

5. Ice Age

Lurgan is built on basalt similar to that of the Giant’s Causeway. It was laid down as lava flows of molten rock (photograph above) that were active some 60 million years ago. In this area, runny basalt lava came to the surface through cracks in volcanoes, where it formed spectacular fissure eruptions (cover photograph). Another igneous rock type called rhyolite is found south of Lurgan and southeast of Moira, where it occurs as a volcanic plugs. These are indicated with a volcano symbol and the rhyolite is coloured yellow on the geology map. Rhyolite is an almost white coloured rock that is very sticky when molten. Its presence tells us that explosive volcanoes were present in the region. The driving force behind Lurgan’s volcanic past was an enormous plume of molten rock that rose up from deep within the Earth. The same process continues in Iceland where volcanic eruptions present serious danger to life.

From about 2.6 million years ago the Earth’s climate changed and caused a series of Ice Ages. The most recent of these ended just 10 thousand years ago, but at its height there was ice thousands of metres thick spread across the landscape (photograph above). It was under this ice that the many small, whaleback-shaped hills, called drumlins were formed in the region. Drumlins are made from a deposit called glacial till that is mostly clay with pebbles, cobbles and even boulders. A digital terrain model (DTM) of the area show the drumlin on which Lurgan is centered (upper picture right) and this fits with the Irish language meaning for Lurgan ‘An Lorgain’ which is “the long low ridge”.

On the DTM the arrow shows the orientation of the drumlin and the direction of ice flow. Though hidden at the back of buildings, basalt cobbles from the glacial till have been used widely as a construction material in the town (lower picture right).

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Permian

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Tree Fern

2. Rock Types

3. Swamps, Deltas and Warm Seas

Sedimentary rocks are made from pieces of other rocks that have been eroded and brought together by wind or water as sediment. When buried deep in the Earth, layers of sand are changed into sandstone and greywacke, whilst layers of shells are turned into limestone (see Section 3 for more explanation).

The limestones and sandstones used in Lurgan’s construction formed between 340 and 310 million years ago during the Carboniferous time period, when the area lay close to the equator. The limestones were laid down in warm tropical seas, home to corals, sea lilies (called crinoids), and shelled animals similar to mussels (known as brachiopods and bivalves). Fossils of these creatures can be found in many of the limestone building blocks used in the town (see buildings trail overleaf). The sandstones contain features called sedimentary structures that show they were deposited by rivers and in swamps that were home to tree ferns, giant dragonflies and early amphibians (picture below). The Scottish sandstones used in Lurgan contain the remains of oil (called bitumen) that was released by the heating of coal deep underground.

Sandstone

Carboniferous

Coral

The outline map below shows that building stone used in Lurgan has been sourced from quarries across Britain and Ireland. It is understandable that locally sourced basalt is by far the most common rock type used, where it has been termed ‘blackstone’ or ‘whinstone’.

Other building stones include sandstone from near Edinburgh, Glasgow and Dumfries in Scotland, and Donegal in Ireland. Sandstone from Dungannon and Limestone from Armagh are also used. Less common rock types include granite from Aberdeen, rhyolite from Tardree near Antrim, Portland stone from the south coast of England, and Larvikite from Norway.

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Lurgan

6. Rocks From?

Rock Record

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T riassic

Jurassic

Dinosaur

Cretaceous Palaeogene Neogene

Quaternary

Period

Greywacke

Limestone

Sources of building stone 1. Aberdeen granite 2. Binny sandstone 3. Giffnock sandstone 4. Locharbriggs sandstone 5. Tardree rhyolite 6. Donegal sandstone 7. Dungannon sandstone 8. Armagh limestone 9. Dunhouse sandstone 10. Portland limestone

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6 Antrim • 5 Donegal • • Belfast Dungannon 7 Armagh • 8 • Lurgan

• Dumfries 9 • Middlesbrough

355 Devonian

Colours used for the geological map and key (centrepiece) match up and show the spread of different rocks across the area. The geological timescale (right) also uses these colours and gives the age of the rocks, with the oldest at the bottom and youngest at the top. Also shown next to the timescale are pictures of past life including dinosaurs and mammoths that existed when the rocks were being formed. Section 2 describes what igneous and sedimentary rocks are and how they form, and provides pictures to help identify the building stones found in Lurgan. The main rock type present under the town is black basalt which is shown as dark pink on the map. The basalts are about 60 million years old and were formed during the Palaeogene time period. More information about the volcanic origin of these rocks is given in Section 4. Sitting underneath the basalt is a white rock type known as chalk that is coloured green on the map. It was formed in an ocean during the Cretaceous time period, between about 100 and 70 million years ago, and is composed of countless microscopic fossils called coccoliths. Below the chalk are orange sandstones and mudstones that are coloured light orange and orange on the map. They were formed in desert environments that existed here between 250 and 200 million years ago in the Triassic time period. The oldest rocks present below Lurgan are grey sandstones and mudstones that are coloured purple and grey on the map. The sandstones are known as greywackes and were laid down in an ocean during the Ordovician and Silurian time periods between 460 and 430 million years ago.

(not shown on map)

Geological Timescale Ancient Life

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Silurian

The rocks on which Lurgan stands tell a story that stretches back some 460 million years into the Earth’s geological history. During that time the area has seen mountains rise and fall, oceans come and go, and has witnessed massive volcanic eruptions. Most recently, during a time period geologists’ call the Quaternary, it has experienced an Ice Age that shaped the land into its current form. The name Lurgan comes from the Irish ‘An Lorgain’ meaning “the long low ridge”, which most likely refers to the presence in the landscape of small hills called drumlins that were formed as glaciers moved from Lough Neagh towards the Irish Sea. Section 5 provides more explanation of the Ice Age and glacial deposits that were laid down at that time.

Glacial sediments

Igneous rocks form when molten rock cools and solidifies. They can be made on land or in the sea from volcanic eruptions of lava, or underground from magma. Igneous rocks used in Lurgan include basalt, rhyolite and granite (see Section 4 for more explanation).

Basalt

Rhyolite

Granite

444 Graptolite

Ordovician

1. Geology

youngest

Geology and Built Heritage Trail

oldest

Lurgan

Key to rock types and deposits in order of age

10 • Weymouth

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Sources of building stone 1. Aberdeen granite 2. Binny Sandstone 3. Giffnock sandstone

6. Donegal sandstone 7. Dungannon sandstone 8. Armagh limestone

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5. Carnegie Library

7. Bank of Ireland

9. Shankill Parish Church

11. St. Peter’s Parish Church

This attractive red brick building was erected in 1906 with an endowment from the American industrialist Andrew Carnegie. The red stone used for the main doorway arch and columns is the Scottish Locharbriggs sandstone from near Dumfries. Look closely and you can see features in the rock called sedimentary structures, including pin-stripe lamination (picture below), that show it was deposited by wind on sand dunes. This sandstone was formed in a desert like the Sahara that existed when Britain and Ireland were positioned just north of the equator.

The ground floor of this bank is faced with Portland stone from near Weymouth on the south coast of England. It was most likely brought by sea to Belfast before being transported to Lurgan. This creamy white limestone has been used for the front of many prestigious buildings including Buckingham Palace and St. Paul’s Cathedral in London and Stormont in Belfast.

Contained within the limestone there are many fossil oysters and other clam-like shells (picture below) that show the rock was formed in warm shallow seas that existed when Britain and Ireland lay much closer to the equator than now.

This Gothic style building is affectionately known locally as “the big church”. A church has stood here since 1725, although the current building mainly dates to the early 1860’s when it was rebuilt and enlarged. It is made from black basalt (blackstone) with yellow buff coloured Dungannon sandstone dressings (picture below).

The impressive tower was made using basalt stone recycled from the ancient Shankill church which formerly stood in the nearby Shankill graveyard. The Dungannon sandstone was laid down in rivers that flowed when Britain and Ireland were positioned close to the equator.

This impressive Gothic Revival style church was constructed in phases between 1867 and 1927 and is the tallest building in Lurgan. Locally sourced, black basalt is the main building stone, whilst light bluish grey limestone from Armagh has been used for doorways, pointed arch windows and the spire. Within the basalt there are small round holes known as vesicles (picture below left).

These were originally gas bubbles that became trapped as the lava from which it formed cooled and solidified. The limestone contains fossilised corals (picture below right) and segments of the stems of sea lilies (see Section 2 overleaf) that show the rock formed in a warm sea.

1 Carnegie Street

13 Market Street

Church Place

70 North Street

6. Ulster Bank

8. The War Memorial

10. Thomas Millar Memorial

12. Brownlow House

This Classical style, three storey, purpose built bank was constructed in 1911. The ground floor features grey Aberdeen granite, whilst the upper storeys are composed of a pale buff yellow sandstone from Donegal. This combination of building stone is shared with its sister banks in Banbridge and Dungannon. Granite is a coarse-textured igneous rock that formed as magma cooled slowly deep underground. It is mostly composed of the minerals quartz and feldspar, whilst the platy, silver and black minerals are mica (picture below).

The War Memorial, unveiled in 1928, records the names of those who have lost their lives in both World Wars and other conflicts. Above a hexagonal base there is a dome and bronze Victory figure supported by columns. Grey Aberdeen granite is the main building stone used, although red granite and marble have been used for the interior paving. The coarse-textured granite is composed mostly of the minerals quartz and feldspar, whilst the platy, silver and black minerals are mica (picture below). Granites are very hard and can be polished, which makes them ideal for use as decorative stone.

This relatively small but elegant memorial was designed by John Robertson. It was unveiled in 1859 as a tribute to the well-respected Reverend Thomas Millar of the First Lurgan Presbyterian Church who tragically died in the Trent Valley Rail Disaster of 1858. It is constructed in the Gothic style from Scottish Binny and Giffnock sandstones, but also features polished red granite and marble. On many of the building stone surfaces there are features called sedimentary structures known as cross-bedding (picture below) that show it was laid down in rivers.

Former home to the Brownlow family, this large Elizabethan Revival style country house

by Edinburgh architect William Henry Playfair, was mostly constructed between 1836 and 1842. It is mainly built from Scottish Binny Sandstone that was obtained from close to Edinburgh and transported to Ireland by canal and sea. The sandstone is grey or buff coloured when fresh, but weathers to a rusty brown in urban settings. On many of the building stone surfaces there are features called sedimentary structures (picture below) that show it was laid down in rivers that existed when Britain and Ireland were positioned close to the equator.

14-16 Market Street

Church Place, Market Street

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Brownlow House 12

Lurgan

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Geology and Built Heritage Trail

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5 Carnegie Library

1. Quaker Buildings, Old Meeting House and Graveyard Robert Street

The old Quaker Meeting House was erected in 1882 and occupies the site of an earlier meeting house. It was in use until 1996 when the current Meeting House in nearby Johnston’s Row was opened. The old Meeting House sits behind a terrace of late 19th century townhouses constructed from locally sourced, black basalt known locally as ‘blackstone’. To the rear is the Quaker graveyard which contains neat rows of headstones composed mostly of grey Aberdeen granite (picture below). Basalt and granite are both igneous rock types. Basalt was formed by rapid cooling of lava flows, whereas the granite formed by slow cooling of magma underground.

Windsor Avenue

3. Town Hall

2-4 Union Street

The Town Hall was designed by Belfast architects Young and McKenzie, and built in 1868 by the Lurgan builder John Archer. The combination of locally sourced black basalt with red brick dressings defines the character of this building linking it back to the underlying geology. The main building material is basalt, which is an igneous rock composed mostly of the minerals feldspar and pyroxene. This fine-textured rock formed on the surface by rapid cooling of molten rock which erupted from volcanoes as lava flows. Some of the basalt surfaces are brown as a result of weathering (oxidation) of iron rich minerals (picture below).

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Bank of Ireland 7

“You and I have trod the backward way To the happy heart of Yesterday, To the love we felt in ages past.

You and I have found it still to last.”

From the poem ‘Affinity’ by George ‘AE’ Russell

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2. First Lurgan Presbyterian Church

4. Danske Bank

The first church building dates to 1827 onto which a Classical style stuccoed façade was added around 1860. To the rear the two storey black basalt hall uses the almost white rhyolite as a dressing stone (picture below). Like basalt, rhyolite is a fine-textured igneous rock that formed by rapid cooling of lava. Look closely at the rhyolite and you will see glass-like crystals in the rock of the minerals quartz and feldspar.

Recent renovation of the pointed arch windows has been completed using the creamy buff coloured Dunhouse sandstone from west of Middlesbrough in England (picture below).

This bank was opened in 1835 and is mostly built from buff yellow sandstone from Dungannon and red brick. Around the entrance it incorporates beautifully carved and polished pillars of black granite known as Larvikite. This beautiful, coarse-textured igneous rock was formed deep underground from magma that was able to cool slowly. It is made up of large crystals of a mineral called feldspar (picture below). This stone is from Norway and is known by many names including Birds Eye Granite, Norwegian Pearl Granite, Blue Norwegian Moonstone and Royal Blue Pearl.

High Street

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1 Quaker Meeting House and Cemetery

How To Use This Guide The look and feel of Lurgan has been greatly influenced by the underlying rocks and landscape on which it has been built, but it also draws from a rich industrial past which saw the use of local and imported stone from across Britain, Ireland and beyond. This pamphlet provides an explanation of the geology on which Lurgan is built, and provides a guide to the main stone types used in twelve of the town’s most historic buildings. A suggested starting point is the Quaker Buildings and graveyard, but the route is circular and can be started anywhere and followed using the numbers and arrows shown on the map above. It is recommended that users read the reverse geology side of the pamphlet before taking the built heritage trail.

39 Market Street

Acknowledgements This resource is produced as part of the Lurgan Townscape Heritage Initiative, supported by the Armagh City, Banbridge and Craigavon Borough Council and The National Lottery Heritage Fund. The pamphlet has been compiled by the Geological Survey of Northern Ireland and British Geological Survey. Geological map, images and other content are ©Crown Copyright unless otherwise indicated. Geology front cover: ; iStock.com/Beboy-ltd. 4. Volcanoes: ©Corel.

5. Ice Age: Ordnance Survey of Northern Ireland Digital Terrain Model © Crown Copyright. 6. Map of the UK and Ireland ©maproom.net. Geological Map and trail map contains Ordnance Survey of Northern Ireland mapping. © Crown Copyright CS & LA 156.

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