These are Foggintor Quarries – close to Princetown. Historically there were extensive granite quarries with their own railway lines servicing them. The quarry opened in 1800 and closed in 1906. The stone was used to build Dartmoor Prison.
The quarries are easy to access either by walking down the old railway line from the main Princetown car park or a short walk from the Rundlestone past Yellowmeade Farm.