Souterrains of Ireland and geology

The maps seems to suggest broadly that the underlying geology plays a big factor in where they are located. I think the underlying geology may also have been a factor in the location of some of the county boundaries also.

It may be tricky to read because of all the different soil / geology types represented.

The map is based on information from the National Monument Service of Ireland, Department of Communities - Northern Ireland Sites & Monuments Record, the Geological Survey of Ireland & Open Street Map Ireland contributors.