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The granite margin from Sticklepath to Bridford, of which the only map hitherto available has been the one-inch Old Series sheet 25 dating from 1866, has been re-mapped, together with the rest of the area lying north-east of the Lustleigh-Sticklepath fault-system (Blyth 1957). Complex faulting in the Lustleigh area is described.
The fracture-pattern consists of a late NW.-SE. fault-system with associated NNW.-SSE. faults, which is superimposed on an earlier series of fractures including joints, aplites, and tourmaline and haematite veins.
The northern part of the Dartmoor granite is visualized as a thick intrusive sheet with an outwardly dipping contact against Lower Culm sediments. More than one episode of movement on the NW.-SE. and NNW.-SSE. faults is postulated, and some part of it is thought to be of Tertiary age. This has resulted in an area of broken granite which has been more readily eroded than the area to the south-west of the faults.
