The Morte Slates are a series of silvery-grey to green coloured slates with some subordinate sandstone and siltstone. A well-developed cleavage has removed what fossils may have earlier been present in these one-time submarine muds. These rocks extend from Morte Point, where they form the coast between Woolacombe and Flat Point, south-southeastwards through West Down and Arlington then east to Withypool. Further east the outcrop broadens to form the Brendon Hills and the rolling country around Clatworthy Reservoir. The eastern extent of the main outcrop reaches the villages of Stogumber and Tolland. An outlier forms the southeastern part of the Quantock Hills between Goathurst and West Monkton.