Stratigraphical data

Kame of Hoy, Orkney, seen from Bay of the Stair

Lexicon of Named Rock Units

The BGS Information Management (Geology) Project maintains Lexicon of Named Rock Units.

This is a database of definitions of rock units and other geological deposits that we recognise in the UK and on its continental shelf.

As well as being a repository of knowledge, the Lexicon is used to constrain the lithostratigraphical attribution of other BGS information systems.

These include DigMap, 3D models, GeoReports, Geology of Britain Viewer, mobile apps, and many more.

The Lexicon holds approximately 19 500 records. A full Lexicon entry includes details of the rock units:

  • age
  • geographical extent
  • lithology
  • lower and upper boundaries
  • name and rank
  • parent unit
  • thickness
  • type localities

The Lexicon can be searched online. It is regularly in the top ten most-viewed pages on the BGS website.

Enquiries about the Lexicon of Named Rock Units should be made to Dr Tim McCormick.

Other BGS stratigraphical resources

BGS Stratigraphic Framework and Lithodemic Scheme Reports

These are the result of cooperation between the BGS Stratigraphy Committee and the Geological Society Stratigraphy Commission, with the aim of reviewing the stratigraphical classification for all parts of Great Britain for which modern information is available. The reports are available for free download in pdf format.

Lithostratigraphic Nomenclature of the UK North Sea

During the 1990s, we worked with the United Kingdom Offshore Operators Association (UKOOA, now Oil & Gas UK) to compile a revision of the existing UK North Sea lithostratigraphical nomenclature, and to establish a new standard scheme.

Seven large format volumes were created, which are now available for free download in pdf format.

Geological Timechart


The Geological Timechart provides colourful reference material, for use in schools, colleges and the home, setting out the geological timescale and geochronological terms used by BGS.


Contact Enquiries for further information about our stratigraphical resources.