The 1:25,000 scale data has been created for two reasons; recent mapping of 'Classic Areas' of British Geology based on the 1:25,000 Ordnance Survey maps, and as part of 'rapid mapping' surveys to speed up the completion of the 1:50,000 scale map series. The 1:25,000 dataset has a small extent but does tend to over areas not yet covered by the 1:10,000 or 1:50,000 data.
The data is made up of four polygon features (or area) layers and one linear features layer. Each polygon is attributed with information based on the name of the unit and its composition. The polygons are arranged into bedrock geology ('solid'); superficial deposits ('drift' or Quaternary); mass movement (mostly landslide); and artificial (or man-made ground). The linear features layer includes thin beds (such as coal seams and fossil bands) faults, mineral veins and some landforms. Coverage of point data, e.g. dips and strikes, is not yet available.