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 and 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

Quaternary Deposits and LandformsThese recent deposits are not on the mapPermian Breccias, Sandstones and Volcanicsgeo-permianbreccias
Tertiary Deposits geo-tertiarydepositsDartmoor Granitegeo-dartmoorgranite
Lundy Granitegeo-lundygraniteCarboniferous Sandstones and Shalesgeo-carboniferoussandstonesshales
Chalk geo-chalkTransition Group (Devonian to Carboniferous boundary)geo-transitiongroup
Upper Greensand and Gault geo-uppergreensandgaultDevonian Slates, Sandstones and Volcanicsgeo-devonianslatessandstonesvolcanics
Lower Jurassic Mudstones and Limestones geo-lowejurassicmudstoneslimestonesDevonian Limestonesgeo-devonianlimestones
Triassic Pebble Beds, Sandstones and Mudstones geo-triassicpebblebedsLower Devonian Schistsgeo-lowerdevonianschists

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-rigsThe 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