North Devon

Abstract

Northern Devon is founded upon sedimentary rocks originally laid down during the Devonian and Carboniferous periods between 290 and 400 million years ago. However, the region was subject to enormous pressures during the Caledonian Oregeny, a period of tectonic plate collision and mountain building, causing the sedimentary gritstones, sandstones and shales to be buckled and folded into some extreme forms, often with near vertical stratigraphy. Consequently, the geology of North Devon is characterised by an east-west anticline and syncline whose crest occurs close to the coast of Exmoor and within which exist a series of smaller folds. The Exmoor plateau rises to around 517 m above sea level and features gently rolling hills with lush vegetation. The coastline features a variety of rock formations, including the highest cliffs in England at around 400 m high, and some of the oldest rocks in the Valley of Rocks area. The rocks themselves vary in density and colouring according to the exposed sedimentary layers, and sometimes exhibit a slaty quality with distinct lines of cleavage. Minerals exist throughout the region, including a vast quantity of haematite ore, running in east-west lodes.