BGS Geology - 250k (DiGMapGB-250) version 4

Data identifying landscape areas (shown as polygons) attributed with geological names. The scale of the data is 1:250 000 scale providing a generalised geology. Onshore coverage is provided for all of England, Wales, Scotland and the Isle of Man. Data are supplied as two themes: bedrock and linear features (faults), there is no superficial, mass movement or artificial theme available onshore at this scale. Bedrock geology describes the main mass of solid rocks forming the earth's crust. Bedrock is present everywhere, whether exposed at surface in outcrops or concealed beneath superficial deposits or water bodies. Geological names are based on the lithostratigraphic or lithodemic hierarchy. This means rock bodies are arranged into units based on rock-type and geological time of formation. Where rock-types do not fit into the lithostratigraphic scheme, for example intrusive, deformed rocks subjected to heat and pressure resulting in new or changed rock types; then their classification is based on their rock-type or lithological composition. This assesses visible features such as texture, structure, mineralogy. Data identifying linear features (shown as polylines) represent geological faults at the ground or bedrock surface (beneath superficial deposits). Geological faults occur where a body of bedrock has been fractured and displaced by large scale processes affecting the earth's crust (tectonic forces). The faults theme defines geological faults (shown as polylines) at the ground or bedrock surface (beneath superficial deposits). The data are available in vector format (containing the geometry of each feature linked to a database record describing their attributes) as ESRI shapefiles and are available under BGS data licence.