This layer of the map based index (GeoIndex) shows the location of available 1:10000 or 1:10560 series paper geological maps. Since the 1960s the standard large scale map for recording geological information has been the Ordnance Survey (OS) quarter sheet, covering a 5km by 5km area. The maps themselves are supplied in different formats depending on their age and the method of compliation or reproduction used. Only the latest and most up-to-date version is listed.