Geology of Somerset - Levels and Moors

Levels and Moors

The North Somerset Levels are to the east of Weston-super-Mare, while the Axe valley is separated by the Isle of Wedmore from the Brue valley. The latter is separated by the Polden Hills from the main wetland of the Parrett/Tone/Cary valleys. The Poldens are a low narrow ridge of Blue Lias with alternating bands of limestone and clay. Because of the nature of the Levels and Moors, the Poldens have a significant visual impact.

The Somerset Levels run from the coast up to 30 kilometres (19 mi) inland. These wetlands cover 600 square kilometres (232 sq mi), most of which is no higher than 8 metres (26 ft) above sea level. There are coastal marine clay deposits, and further inland there are many peaty areas. Dotted within this wetland landscape are slightly raised inter-glacial "islands" called burtles. These have been settled from the Mesolithic onward, with wooden causeways linking them to higher ground. There are also rocky outcrops, such as Brent Knoll and Glastonbury Tor which have also housed ancient settlements.

The water levels in the moors and levels are controlled by a series of small narrow canals called rhines (in Avonmouth and Gloucestershire), or rhynes (in Somerset) (both pronounced reens), or reens (in Monmouthshire), along with larger drains, gates and pumping stations. The rhynes are often used as field boundary ditches instead of hedges. Some parts are allowed to flood in winter. The area is mainly used for grazing but some peat extraction is carried out.