A brief account of the local geology around the Cottage Hotel, Hope Cove, Devon. This formed part of a geological field trip organised by the Open University Geological Society, Oxford Branch, in June 2008, with leaders Professor John Mathers and Dr Jenny Bennett. By Dr L A Runnalls.
Hope Cove has the oldest rocks in Devon, which date from the Lower Devonian Period, between 395 and 310 million years old. These are metamorphic rocks, rocks that have been changed by pressure and temperature during deep burial in the earth's crust. There are three rock types to be seen in this area: the older green schist, a slightly younger (80ish million years!) grey slate and a distinctive rock called Mylonite.
The base of the Shippen is formed from the older, 395 MA rocks. These have been subjected to temperatures in the range of 400 to 500° C and to pressure equivalent to depths of between 8 and 30 kilometres. They are generally of a green colour and are known as "Green Hornblende Schist".
The top of the Shippen is covered with Pleistocene deposits of about 2 million years old.
The young, 310 MA, grey slate is placed on a slab of the older, 395 MA, green Hornblende Schist.