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. 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. To produce this dataset, the twenty one 1:100,000 paper maps covering Ireland were digitised and borders and overlaps between map sheets were removed. We collect new data to update our map and also use data made available from other sources. This Bedrock map is to the scale 1:100,000 (1cm on the map relates to a distance of 1km). 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, its description, stratigraphy code (rock layers with age profile), lithology code (rock type) and map sheet number. Each polygon is linked to the bedrock lexicon table which has more detailed information such as a definition of the rock unit, rock types, age, thickness and other comments.
The data holding comprises 4 key shapefiles: 1) Bedrock Rock Units 1:100k - A polygon shapefile that contains bedrock geological information on Stratigraphy, Igneous, Lithology and Diagentic codes, their unitnames and brief descriptions. 2) Bedrock Stratigraphic and Structural lines 1:100k - A linework shapefile that contains structural geological linework codes, stratigraphic geological line codes and descriptions and map sheet cross sections as per paper printed maps. 3) Bedrock Structural Symbols 1:100k - A point shapefile that contains selected structural data from the 19th century 6" mapping. 4) Bedrock Outcrop - A polygon shapefile that contains outcrop locations from the 19th century 6" inch mapping and other sources such as mineral exploration reports Two lexicon tables are also included in the download and are related to the linework and polygon files to provide more detailed information on the represented geological formations.