All-Ireland 1:500,000 Quaternary Geology Map

 Quaternary All-Ireland Map   The Quaternary Period is the most recent period in the geologic time scale of the International Commission on Stratigraphy. This period, covering the last 2.6 million years, is subdivided into two epochs: Pleistocene (2.6 million to 10,000 years before present (BP )) and the Holocene (10,000 years BP to the present). lreland was affected by a number of glaciations during the Pleistocene. The most recent glaciation, stretching from 115,000 years ago to the Holocene, gave rise to most of the Quaternary sediments we see today. The erosive power of the last ice sheet removed much of the evidence for earlier glaciations.

Ireland has a very rich legacy of glacial deposits and landforms. Glacial landforms, associated with the direct action or melting of ice, include ice-sculpted bedrock from glacial erosion and ice-moulded glacial deposits expressed as drumlins, moraines and eskers. Mapping the shape and the spatial distribution of these landforms aided the reconstruction of the glacial history of Ireland. More than 85% of the Irish land surface is covered by sediments of Quaternary age. Postglacial sediments, covering a fifth of the land surface, were mostly deposited during the Holocene and include lacustrine and alluvial plains, peat bogs and coastal landforms.
The All-Ireland Quaternary geology map at 1:500,000 scale presented here is an amalgamation of Quaternary maps from Ireland and Northern Ireland. Data from the Geological Survey of Ireland, the Geological Survey of Northern Ireland and the relevant literature were compiled, homogenized and simplified to produce a seamless dataset comprising sixteen sediment types. Tills are further classified by their dominant lithology in eight different classes. Tills are tightly packed, unsorted, unbedded, glacial deposits possessing many different particle sizes with commonly sharp, angular to sub-angular clasts. Till forms beneath a glacier as it erodes the bedrock or pre-existing sediment that it is flowing over. Soil geochemistry and radiometrics data from the Tellus and Tellus Border projects were used to subdivide undifferentiated till deposits in Northern Ireland to match the till types mapped in Ireland. Furthermore, the location of key sites with Quaternary and pre-Quaternary dated sediments and four main geomorphological features consisting of drumlins, eskers, onshore moraines and off-shore proglacial terminal moraines are presented in this map.