The northeastern part of the Dartmoor granite mass in southwest England is traversed by a series of northwest-southeast valleys following fault lines. The name Lustleigh fault is proposed for the southeastern end of a major fault zone along a northwest line between Lustleigh and Sticklepath. The characteristics and evidence of the faulting are described. Some of the movement, if not all, occurred in Tertiary time, although dislocation may perhaps have been at the end of the Carboniferous. In the discussion, the initiation of the faulting is placed during the final consolidation phase of the granite and is considered due to uplifting.