The effects of thousands of years of weathering though wind, rain, frost, lichen and algae have all played their part in making this 'X'-shaped pattern in the fractured granite at Hound Tor. In fact large granite boulders litter the edges of most of the tors like scree, indicating that the tors were once very much higher. It is uncertain how Dartmoor fared in the last Ice Age, being thought to have been an area of tundra to the south of the main Ice Sheet which touched the North Devon coast near Barnstaple; but just maybe there were local glaciers up here...