Aquifer, shale and clay maps

Four types of maps are available to view.

Aquifer occurrence maps

There are eleven principal aquifers in England and Wales and the distribution of each of these at the surface and below ground is shown in a series of aquifer maps. The maps include information on the depth to the base of the geological units that form each of the principal aquifers, as well as interpretive information about the principal aquifers.

Shale and clay occurrence maps

Maps have been produced for the six major shale or clay units in England and Wales. The distribution of each of these is shown on separate shale and clay maps which include information on the depth to the top of the shale/clay unit. There is also associated interpretive information about each of the shale or clay units.

Aquifer/shale separation maps

A series of 25 aquifer/shale separation maps show where the principal aquifers overlie a shale or clay unit. Each map shows a relative estimate of the vertical separation between the base of a given aquifer and the top surface of a given shale of clay below that aquifer. Basic interpretive information about the separation maps is also available.

National overview maps

Two national overview maps are available. One shows the extent or area over England and Wales where rock units that are designated as principal aquifers by the Environment Agency are present at the surface and below ground. The second map shows the extent of the six major (potentially gas-bearing) shale units present at the surface and below ground.

Notes

OD refers to Ordnance Datum. It is the common reference level against which all vertical elevations (heights) on maps are related to. As a simplification it can be considered as equivalent to sea level. On the maps published by BGS, where a height is given as a positive number then this is above OD and where negative below OD.