The Upper Devonian Rocks of The Chudleigh Area, South Devon

Abstract

I. Introduction The Upper Devonian rocks under consideration occupy a small portion of the area of the 1-inch geological map (Sheet 339). They occur as small faulted inliers on the north-eastern side of the Bovey basin in a region otherwise occupied by Culm overlain by Permian and Cretaceous strata. The main (Chudleigh) outcrop, which is a mile across at its widest part, extends from the neighbourhood of Harcombe to Chudleigh Rocks—a distance of about miles. East of this outcrop, and on the same latitude as Chudleigh, is the small triangular patch of Lower Dunscombe, and farther south lies the much larger but partially concealed Ugbrooke-Well inlier, which appears on the map as three detached outcrops. The nearest edge of the Dartmoor granite lies about miles to the west. The Devonian inliers include the upper part of the Massive Limestone of South Devon thrust over thinly bedded limestones and shales. The Massive Limestone is here shown to be Lower Frasnian and the thinly bedded limestones and shales Upper Frasnian and Famennian respectively. The Kate Brook, the main stream in the area, has cut its valley along the main outcrop of the Famennian shales. The lowest part of the valley lies below the 100-foot contour. The Massive Limestone flanks the depression on the east, rising to 300 or 400 feet; the surrounding Culm forms undulating ground 400 to 500 feet high. The Permian with its Cretaceous capping rises to 700 feet in the north-east. My thanks are due to Lord