Heritage sites of Co. Roscommon
“This Cistercian monastery was founded in the twelfth century by monks from Mellifont Abbey under the patronage of the local ruling family, the MacDermotts. It was one of the most powerful of the early Cistercian foundations in Ireland and among the foremost in Connacht. Cromwellian forces wreaked devastation when they occupied the abbey in 1659. It was further mutilated during the following centuries, when it was used to accommodate a military garrison. Despite all the violence it has suffered over the centuries, Boyle Abbey is well preserved and retains its ability to impress…”
Read more about the history of Boyle Abbey on Heritage Ireland
Stone from St. John’s Hole, located close to Boyle, was used for all classes of work at Boyle Abbey, including the carved mouldings. This hard, grey sandstone is Carboniferous in age and is situated in the Boyle Sandstone Formation.
In George Wilkinson’s Practical Geology and Ancient Architecture of Ireland, published in 1845, he stated: ‘On the north side of the river [River Boyle], at a place called St. John’s Hole, a good sandstone of a greyer colour is quarried; and chiefly from a very large and deep hole in the river, where the quarry was originally worked, is supposed to have been obtained the stone used in the construction of the abbey at Boyle. In the ruins of the abbey there is excellent work of every kind, from common plain dressed stone, to carved mouldings and ornaments; and its lofty arches display a skill in construction far superior to the masonry of the present day. The stone has resisted exposure to the weather well, some of the marks of the tool being still visible. It is supposed that the beds from which the stone was obtained were more easily worked than those now above the water, nor is the supposition improbable; and it is likely that by well-diverted efforts, the bed of the river was temporarily diverted in order to get at these stones which, from being constantly saturated, had not become so hard at that which was comparatively in a dry position. The stone in its present state is certainly very hard.’
In 2004 Carrig Conservation International Ltd. was appointed by the Office of Public Works to undertake conservation of Boyle Abbey’s church. Some new dressed stone was provided and damaged stone was repaired as required. The project was completed in 2011. Read more here.
Geology of Co. Roscommon
The oldest rocks in Roscommon occur in two inliers (older rocks entirely surrounded by younger rocks) north-east of Strokestown and at Slieve Bawn. These rocks are of Ordovician age and are the remnants of a former ocean floor and the roots of a long since vanished mountain chain. They are related to rocks throughout Longford, Down and into the Southern Uplands of Scotland, but as they are so small in Roscommon that their story is best told in the other county’s descriptions.
Surrounding them are some Devonian age rocks, sandstones and gravels laid down by flash floods in a poorly vegetated environment. Both Ordovician rocks and Devonian rocks are partly preserved because they have been lifted up on one side of the Strokestown Fault, which is one of the major geological structures in the county.
Roscommon’s main geological history is in the Carboniferous period. Nearly all the county has limestone near the surface, which was deposited in a shallow tropical sea covering much of Ireland around 330 million years ago. Thick beds of limestone occur and are continuous over a very wide area. In the uplands around Lough Allen (shared with Leitrim and Cavan) there are younger Carboniferous rocks that were deposited in a delta environment. These include sandstones and shales with occasional beds of coal and some ironstone nodules.
Some glacial deposits obscure the limestone but it is generally a thin skin. Parts of Roscommon have now been recognised as having karstic features, like caves and swallow holes in the limestone, where water mostly drains underground. In the south-east part of the county conspicuous wooded ridges of glacial gravel, called eskers, are found. These were deposited by rivers that flowed beneath the ice sheets, and were left as sinuous ridges once the ice melted. Many small quarries have worked these gravels for aggregate.
Further reading: L. Dunne & J. Feehan 2003. Ireland’s Mushroom Stones. Relics of a Vanished
Lakeland. Environmental Resource Management, University College Dublin.
Map legend: Geological Map of Limerick (based on GSI 1:1,000,000 map 2003). Pink: Ordovician; Pale green: Silurian; Beige: Devonian sandstones and conglomerates; Dark blue: Lower Carboniferous sandstones; Pale blue: Lower Carboniferous limestone; Dark green: Upper Carboniferous shales.