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

Data identifying landscape areas (shown as polygons) attributed with geological names and rock type descriptions. 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. 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. The bedrock geology of Great Britain is very diverse and includes three broad classes based on their mode of origin: igneous, metamorphic and sedimentary. The data includes attribution to identify each rock type (in varying levels of detail) as described in the BGS Rock Classification Scheme (volumes 1-3 ). The bedrock has formed over long periods of geological time, from the Archean eon some 7500 million years ago, to the relatively young Pliocene, 58 million years ago. The age of the rocks is identified in the data through their BGS lexicon name (published for each deposit at the time of the original survey or subsequent digital data creation). For stratified rocks i.e. arranged in sequence, this will usually be of a lithostratigraphic type. Other rock types for example intrusive igneous bodies will be of a lithodemic type. More information on the formal naming of UK rocks is available in the BGS Lexicon of Named Rock Units. Geological names are based on the lithostratigraphic or lithodemic hierarchy. The lithostratigraphic scheme arranges rock bodies 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, using visible features such as texture, structure, mineralogy. 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.