Geology

The Geological Heritage of County Offaly 2016

in 2016 Laois and Offaly County Councils worked with the Geological Society of Ireland to carry out a survey of geological sites in the two counties. The audit was carried out by Ronan Hennessy, Robert Meehan, Matthew Parkes, Vincent Gallagher and Sarah Gatley. The Offaly Geological Heritage Project was supported by the Heritage Council, the Geological Survey Ireland and the Offaly County Council. The resulting report was an action of the County Offaly Heritage Plan 2012-16. Download the Geological Heritage of County Offaly, An Audit, 2016The individual site reports can be accessed here.

The Geology of Laois and Offaly  by John Feehan, 2013

The last thirty years have seen much new research on the geology of Laois and Offaly, shedding new light on – and providing fascinating new insights into – the landscape heritage of the two counties. John Feehan has remained in close touch with this research since his own work on Slieve Bloom as a post-graduate student in the Department of Geology at Trinity College in the late 1970s and early 1980s.

In this magnificent volume John now brings all of this research together for a general readership, and relates it to the broader cultural heritage of Laois and Offaly in a chapter that looks at Geology in our Lives. Separate chapters review the story of the two counties through the successive geological epochs that have a bearing on their evolution. A special chapter written in collaboration with Donal Daly of the Environmental Protection Agency (and like John himself a native of Offaly) looks at the Geology of Water. A special feature of the book is the six specially commissioned paintings illustrating different periods in the geological evolution of Laois and Offaly, by Offaly-based artist Jock Nicol, reproduced here as two-page full-colour plates. The paintings themselves will be exhibited during the launch of the book.

The Geology of Laois and Offaly is published in hard cover format, some 400 pages long, 21cm x 31cm (Portrait) size, profusely illustrated throughout, in full colour. The price is €40.00 and one can be ordered in any book shop (through Argosy distribution) and it is currently in stock in Midland Books, High Street and Balcony Books in the Bridge Centre and Offaly History on Bury Quay, all in Tullamore and in Supervalu in Birr.  See the review in Science Spin 2013

Geological Videos by John Feehan

Offaly in the Late Devonian

The Silurian Period in Offaly

The Ice Age in Offaly

Offaly After the Retreat of the Glaciers

The Lower Carboniferous History of Offaly

The Marble of Clonmacnoise, Limestone Quarrying at Clerhane, (Clorhane), Shannonbridge, Co. Offaly by Declan Ryan

This book is now available in Shannonbridge, or from the OHAS on Bury Quay, Midland Books on High Street, Robbins Bookshop off O’Connor Square all in Tullamore.  Alternatively €10.00 can be posted to Offaly County Council  and a copy will be sent out.  The book describes Clorhane townland and the surrounding area and tells the story of the quarries, their owners and the craftsmen who worked there from early records, to their heyday, decline and eventual closure. The type of stone, the work of cutting and carving and the resultant output and the many fine buildings to which they contributed are also examined.

Please note much of the land is in private ownership and permission should be sought from landowners before entering. If in doubt please contact heritage@offalycoco.ie

‘Of the many quarries that operated in Offaly during the centuries before stonecraft declined and almost ended with the arrival of modern concrete, few enjoyed greater prestige than Clerhane, whose crinoidal limestone is one of the most beautiful of Irish building stones. In his meticulous study of the stone industry at Clerhane Declan Ryan has  painstakingly salvaged all that survives from oral record and tradition and the documentary record, and set this against the physical background of the quarries themselves and their geographical context. In highlighting the achievement of the quarrymen of Clerhane this lovely book will do much to draw appreciative attention to this aspect of the environmental heritage of one of the most remarkable places in Offaly, and stimulate comparable attention to other facets of that heritage. John Feehan, Syngefield, Birr.

Mining in Offaly

Until recently there were no recorded mines in Offaly. However following the collapse of a mine shaft in Blundell Hill, Edenderry in September 2011, Dr Martin Critchley and Dr Sharon Schwartz have carried out research into this mine which was seeking lead and silver deposits. See their YouTube clip - Offaly Heritage Blundell Mine. Download Blundell Hill Report 2011.

Field Trips

Some years as part of the Offaly Naturalists' Field Club programme there is a geology weekend in late summer led by John Feehan. There is an introductory talk on the Friday night and field trips on the Saturday and Sunday. Email heritage@offalycoco.ie for details.

Wavestone / Mushroom Stones

After the last Ice Age, the water table was considerably higher than it is today. Wavestone/ Mushroom stone is the name given to a limestone rock which has wave marks on it which indicate this water level. Some are shaped like mushrooms, others have an overhang facing in just one direction but all are notched and undercut in such a fashion as to suggest prolonged exposure to standing water at some time in the past. These help us to decipher where the ancient shore lines were.

To find out more about these unusual features of the Offaly landscape download the publication Ireland's Mushroom Stones, Relics of a Vanished Lakeland Louise Dunne and John Feehan. 2003. This can be downloaded - due to the size of it, it is in three parts part 1(6MB), part 2 (8MB), part 3 (6MB)

If you know of a location of a wavestone or mushroom stone in your area please check if it is in the 2003 publication and if not please email the heritage@offalycoco.ie. John Feehan and Louise Dunne are updating this publication to incorporate the new finds and information since 2003.

Endrim mushroom stone

The mushroom stone at Endrim.

 

Eskers

The last ice age was around 15,000 years ago. Rivers flowed under the ice as the ice began to retreat. These rivers built up jumbled layers of sand and gravel that now form ridges in the landscape called eskers. Other eskers were formed by ribbons of water between the melting glaciers. The sand and gravel in these eskers is sorted. Eskers are particularly evident in Offaly. Knockbarron esker complex close to Kinnitty is a superb example. Roads often travel along eskers for example you will experience this on the road from Boher to Clonmacnoise and along the High Road in Durrow.

The Offaly Heritage Foum commissioned a Study of Eskers west of Tullamore in 2006 which was carried out by Mary Tubridy and Associates.