Devon’s rocks: a geological guide

This webpage contains guides to 13 different rock types found in Devon. We hope you find the information provided is appropriate for your requirement, either for leisure or study. Different levels of information are provided, which are designed for those with a general interest in rocks, along with more advanced technical descriptions.

Click on the map to enlarge, click on the rock name in the key below to open a PDF which contains:

  • a basic description of the rock type
  • a more technical explanation of the geology
  • photographs of the rock type
  • how the rock type has been used
  • recommendations of where the rock type can be visited.

Summary map of the geology of Devon

Devon geology map

Rock type Map key Rock type continued Map key continued
Quaternary Deposits and Landforms These recent deposits are not on the map Permian Breccias, Sandstones and Volcanics Geo Permian breccias
Tertiary Deposits  Geo Tertiary deposits Dartmoor Granite Geo Dartmoor Granite
Lundy Granite geo Lundy Granite Carboniferous Sandstones and Shales Geo carboniferous sandstones and shales
Chalk  Geo Chalk Transition Group (Devonian to Carboniferous boundary) Geo transition group
Upper Greensand and Gault  Geo upper greensand gault Devonian Slates, Sandstones and Volcanics geo Devonian slates, sandstones and volcanics
Lower Jurassic Mudstones and Limestones  geo lower Jurassic mudstones limestones Devonian Limestones Geo Devonian Limestones
Triassic Pebble Beds, Sandstones and Mudstones  Geo triassic pebblebeds Lower Devonian Schists Geo Lower Devonian schists

An Introduction to the Geology of Devon travels back in time and summarises the history and variety of geology in Devon. A document called Devon’s Rocks – A Geological Guide provides a compilation of all 13 rock type guides. The Educational Register of Geological Sites is designed to encourage the educational use of Devon’s fascinating and diverse geological and geomorphological heritage.

Visiting geological sites

devon-rigs The information on this page was developed in celebration of the International Year of Planet Earth in partnership with the Devon RIGS Group. The 13 guides to the rock types were written by a team of consultants within David Roche GeoConsulting. The basic description sections have been subsequently edited by Devon County Council.