Geology of Lancashire

This article covers the modern ceremonial county of Lancashire which includes the boroughs of Blackpool and Blackburn with Darwen but not those southern parts of the historic county of Lancashire which have since 1974 formed a part of the counties of Merseyside and Greater Manchester nor the northernmost part which now forms a part of Cumbria.

The geology of Lancashire in northwest England consists in the main of Carboniferous age rocks but with Triassic sandstones and mudstones at or near the surface of the lowlands bordering the Irish Sea though these are largely obscured by Quaternary deposits.