The counties included in this area are Cornwall, Devon and Somerset together with the four administrative areas around Bristol (formerly Avon) and the Isles of Scilly.
Much of the landscape of Devon and Cornwall consists of plateaux at varying levels. The plateaux surfaces reach the sea in cliffs, for which the area is famous, but with a few areas of sand dunes as well. The plateaux are deeply incised by rivers and many of the lower river valleys have been submerged to form picturesque estuaries such as the Dart and Tamar. The highest areas coincide with the granite outcrops forming Dartmoor and Bodmin Moor and reach 621 metres on Dartmoor.
The high ground of Exmoor, made up from gritstones and slates, reaches 521 metres at its highest point. It lies in the counties of Devon and Somerset. To the east of Exmoor are the low lying Somerset Levels. This is an area similar to the Fens, which lies just above sea level and in the past was subject to flooding. To the south of Bristol lie the Mendip Hills, which is an area of limestone rocks. The porous nature of the limestone has lead to a lack of surface streams with most drainage underground. Extensive underground caverns have been formed, perhaps the most famous being at Cheddar.
The Isles of Scilly, which lie 40 km to the west of Cornwall, total approximately 18 square km. St Mary's is the largest island and has a highest point of 51 metres.