The Group's aim is to identify, survey, protect and promote geological and geomorphological sites in the former County of Avon - the modern unitary authorities of Bath and North East Somerset, Bristol, North Somerset and South Gloucestershire. RIGS are selected for their educational, research, historical and aesthetic value.

Geology of the Avon region

The following summary is taken from English Heritage’s 'Strategic Stone Survey: A Building Stone Atlas of Avon'. This is an excellent and free resource, and can be accessed here http://www.bgs.ac.uk/mineralsuk/mines/stones/EH_atlases.html

The solid geology of Avon is complex. The sequence is dominated by sedimentary rocks which range from early Ordovician to late Jurassic in age; a few minor volcanic rocks also occur interbedded with Palaeozoic sediments in the Weston-super-Mare and Tortworth areas. In very general terms, the geology can be regarded as younging from west to east, but numerous unconformities and faults create a complicated outcrop pattern of inliers, outliers and a varied topography. The geological heritage of Avon is very diverse – it includes a number of classic localities such as the Avon Gorge which have been highly instrumental in the development of British Lower Carboniferous stratigraphy, and the former Somerset and Bristol Coalfield which played a key role in the economic and social development of the region.

To find out more, click here to read Natural England's superbly detailed guide to the geology of Avon.
Geological map of the Avon region (BGS)

In terms of RIGS, our remit includes well known sites such as:
  • Aust Cliff [South Gloucestershire] sediments showing the transition between Triassic and Jurassic, exposures of the Westbury Bone Bed
  • Avon Gorge [Bristol] stunning gorge through Carboniferous limestone
  • Barnhill Quarry [South Gloucestershire] unconformity between Carboniferous and Triassic, with fossil stromatolites and ripple beds
  • Burrington Coombe [North Somerset] section through Devonian sandstones and Carboniferous limestone
  • Radstock quarries [BANES] unusual Lower Jurassic lithologies and fossil spiders, ferns and dragonflies
  • Sand Bay [North Somerset] intercalated limestones and tuffs, and altered basaltic pillow lava

Aust Cliff. Photo credit: Dave Villis