Bedrock is the solid rock at or below the land surface. Over much of Ireland, the bedrock is covered by materials such as soil and gravel. The Bedrock map shows what the land surface of Ireland would be made up of if these materials were removed. As the bedrock is commonly covered, bedrock maps are an interpretation of the available data. The faults show the details of the structural geology. Faults are the result of great pressure being applied to rock across a whole continent or more. These rocks will break under the pressure, forming faults. Faults are recorded as lines where the break in the rock meets the surface.

Geologists map and record information on the composition and structure of rock outcrops (rock which can be seen on the land surface) and boreholes (a deep narrow round hole drilled in the ground). Areas are drawn on a map to show the distribution of rocks. Lines are drawn on a map to show the faults.

To produce this dataset, the Geological Survey Ireland (GSI) bedrock geology 1:500,000 and 1:100,000 maps were generalised. The Northern Irish data was generalised using the Geological Survey of Northern Ireland (GSNI) 1:250,000 bedrock geology map.

This Bedrock map is best displayed to the scale 1:1,000,000 (1cm on the map relates to a distance of 10km).

It is a vector dataset. Vector data portray the world using points, lines, and polygons (areas).The bedrock data is shown as polygons. Each polygon holds information on the rock unit name, age and there is a link to download a pdf of the age description. The faults data is shown as lines. Each line holds information on the fault name if one exists.