Somerset is a rural county in the southwest of England, covering 4,171 square kilometres (1,610 sq mi). It is bounded on the north-west by the Bristol Channel, on the north by Bristol and Gloucestershire, on the north-east by Wiltshire, on the south-east by Dorset, and on the south west and west by Devon. It has broad central plains with several ranges of low hills. The landscape divides into four main geological sections from the Silurian through the Devonian and Carboniferous to the Permian which influence the landscape, together with water-related features.
The low-lying areas of the North Somerset Levels and Somerset Levels have been subject to thousands of years of flooding and man's attempts to control the flow of water. In the north of the county the Limestone of the Mendip Hills dominates the landscape, while in the south the Blackdown and Quantock Hills rise out of the levels. The highest areas are on Exmoor. The wide variety of landscapes has led to several areas being designated as Sites of Special Scientific Interest for geological reasons, and support a range of flora and fauna as can be seen from the List of Sites of Special Scientific Interest in Somerset.