Irish Quaternary Geology Map

A major initiative to compile and synthesise available Irish Quaternary geology data for Ireland has just concluded. Many strands of data on Ireland’s Quaternary geological history have been weaved together into a new set of maps. The results from these recent efforts to develop new Quaternary geology maps of Ireland are now freely available and ready for download and use in GIS software here.

The data includes the Quaternary sediment map (delineating the different types of Quaternary sediment units), Quaternary geomorphology map (showing the landscape features that developed in Ireland over the course of the Quaternary Period) and the Quaternary confidence map (showing different levels of confidence in the Quaternary sediment map). All data has been compiled for use at the scale of 1:50,000.

The Quaternary Sediment map shows the spatial relationship between almost 70 different types of glacial and post-glacial deposits. The map has over 200,000 individual polygons (map units). This map is the most extensively used dataset in this suite of products. In applied geology, the geological modelling the spatial distribution of a wide range of natural phenomenon rely on these data as a controlling factor.

The Quaternary geomorphology map describes and categorises the erosive and depositional features that shaped Ireland’s glacial landscape. Over 55,000 individual features have been mapped using detailed aerial photography and digital elevation models for the whole country. The known relationships between geomorphology and geological process allows reliable inferences to be made about the sediment assemblage that can be found in and around these features, in this way the Quaternary geomorphology map is both a useful tool for informing and reading the Quaternary Sediment map. These data can also help us understand the growth and decay of the ice-sheets and other palaeo-climactic systems.

Exposure of cut away peat overlying stony diamicton with angular limestone cobbles and boulders.

Photograph taken from an Esker ridge in the Irish midlands running west-east.

Sandy Bouldery till derived from Lower Carbonifereous Limestone.

Flood plain flat poorly drained ground composed of silts and

Exposure showing a fine example of glaciodeltaic sediments in the Irish Midlands.
Crossbedding correspond to foresets dipping NNE composed of interstratified silts,
sands and granules overlain by horizontally bedded gravels interpreted as the
topset facies of a glaciolacustrine deltaic deposit.

Exposure of esker ridge cross section displaying poorly stratified cobble and boulder gravel.

There is a substantial amount of detail within these map datasets but there is still a lot more to learn about the nature and distribution of Irish landforms and sediment assemblages. GSI is always keen to hear from interested parties about the kinds of observations that underpin Quaternary mapping including temporary exposures into Quaternary sentiments and interesting Quaternary landforms. Modern Quaternary maps are not static snapshots of our understanding of Quaternary geology; in fact they are rather dynamic and can evolve and change on the basis of new observations. Please contact us if you have information on these topics. Taking advantage of the extensive and detailed information generated over the course of the Tellus Project: Summer 2016 will see new field mapping to help update our understanding of the Quaternary geology over a study area covering parts of Counties Cavan, Leitrim, Longford, Monaghan Roscommon and Westmeath.

 This survey will involve the use of:

  • Shallow geophysical surveys using Ground Penetrating Radar (GPR) and Electrical Resistivity Imaging (ERI) systems. GPR involves dragging the system on the ground to record subsurface discontinuities. ERI measures the subsoil conductivity from electrodes placed on the ground
  • Shallow drilling six inches diameter boreholes bored by a drilling rig mounted on a 4-wheel drive lorry. Boreholes are up to 20 m deep and are filled in after drilling.
  • Exposure recording consisting of description of shallow sediments exposed at surface and collection of samples to carry out further lab analyses.

N.B. The Quaternary mapping project is not a commercial mineral exploration programme nor is it related to fracking, pylons or wind-farm development.

Please see our outreach poster here.