Coastwise members spend much time poking around the local rock pools and countryside, so an overview of how the geology of our singular coast came to be is of much interest.
Local geologist Margaret Sutcliffe gave members a 4-dimensional view of the coast, both by location and time. Margaret covered Lynton's Valley of Rock and points West to illustrate the variation in geological period from Carboniferous through the Devonian along our coast.
The local weathered shales and sandstones were crumpled into their characteristic folds by the Variscan mountain-building period in the Permian era, when they were under a mountain range possibly as high as the present Himalaya, since completely eroded.
Fremington Quay, in the Upper Carboniferous, shows lignite (a low-grade coal), which contrasts with the high-grade Welsh coal measures of a similar era just across the Bristol Channel which were formed by dense forests at the edge of an ancient continent. In what is now N.Devon we are just on the edge of that adjoining sea, where a large river probably deposited vegetation in deltaic deposits after storms.
Lundy, just a few miles offshore, is completely different, being "just" 50M years old, and the result of volcanic activity which was nothing to do with the Dartmoor basolith upwelling.
Local geologist Paul Madgett helped with some of the detail, and members enjoyed the lively and very educating discussion.