A series of maps at the detailed scale of 1:25 000 have been produced for areas of outstanding geological interest in Great Britain. Some maps are accompanied by explanatory booklets. The maps were published between 1954 and 2007. About 60 maps have been published, some showing solid geology, some drift geology and some combined solid and drift. Most of the maps include geological cross sections and generalised vertical sections. Geological maps represent a geologist's compiled interpretation of the geology of an area. A geologist will consider the data available at the time, including measurements and observations collected during field campaigns, as well as their knowledge of geological processes and the geological context to create a model of the geology of an area. This model is then fitted to a topographic basemap and drawn up at the appropriate scale, with generalization if necessary, to create a geological map, which is a representation of the geological model. Explanatory notes and vertical and horizontal cross sections may be published with the map. Geological maps may be created to show various aspects of the geology, or themes. These maps are hard-copy paper records stored in the National Geoscience Data Centre (NGDC) and are delivered as digital scans through the BGS website.