Geology

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.

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.