Map based index (GeoIndex) 1:50000 series paper geological map availability

This layer of the map based index (GeoIndex) shows the availability of 1:50000 series paper geological maps. For England and Wales (and Northern Ireland), map sheets normally cover an area 30 km east-west and 20 km north-south; in Scotland the coverage is 20 km east-west and 30 km north-south. The 1:50 000 geological map grids are based on an early Ordnance Survey 1:63 360 (one inch to one mile) scale map grid and are not related to the current Ordnance Survey 1:50 000 map sheets. Maps are normally available in both flat and folded formats.

本层地图索引（地理索引）展示了1:50000系列纸质地质图的可用性。针对英格兰、威尔士（以及北爱尔兰），地图通常覆盖东西方向30公里、南北方向20公里的区域；在苏格兰，覆盖范围为东西方向20公里、南北方向30公里。1:50 000地质图网格基于早期的大比例尺军事测绘1:63 360（一英寸等于一英里）的地图网格，且与当前的大比例尺军事测绘1:50 000地图图幅无关。地图通常以平铺和折叠两种格式提供。