Tor on Dartmoor. Dating of 28 tors on Dartmoor showed that most are surprisingly young, less than 100,000 years of surface exposure, with none over 200,000 years old. They probably emerged at the start of the last major ice age (Devensian). By contrast the Scottish Cairngorms, which is the other classic granite tor concentration in Britain, the oldest tors dated are between 200 and 675 thousand years of exposure, with even glacially-modified ones having dates of 100–150,000 years. See also References Further reading Rock formations Weathering landforms