Courtesy of the University of Iceland
Moraines are accumulations of rock and debris that have been carried by ice sheets and glaciers. The material may be unsorted or at best poorly stratified (in contrast to the water-formed eskers).
Moraines may be spread across the countryside as ‘ground-moraine’ or may have a more distinct landform expression. When either a glacier or an ice sheet reaches their maximum extent, the material being pushed in front forms a distinctive ridge of rock and debris called a terminal or end-moraine. This feature may be up to 50 metres high and has a steep side at its front. As the ice begins to retreat toward the end of a cold phase, recessional moraines may form, marking points of readvance or maybe a halt in the retreat.
In Ireland, the end-moraine associated with the maximum extent of 'Midlandian' ice (reached about 70,000 years ago) has been mapped as a zone of hummocky country stretching across Ireland from west Limerick through south Tipperary. It then heads north and banks against the western flanks of the Wicklow mountains before curving around them and running southwards close to the Wicklow-Wexford coastline. Another moraine lying further north and also stretching through the south midlands is considered to represent the maximum extent of ice during the most recent cold stage about 16,000 years ago. Much more localised moraines are also identifiable associated with mountain ice caps, valley glaciers and individual corries.