Somerset levels

The Somerset Levels are a coastal plain and wetland area of Somerset, England, running south from the Mendips to the Blackdown Hills.

The Somerset Levels have an area of about and are bisected by the Polden Hills; the areas to the south are drained by the River Parrett, and the areas to the north by the rivers Axe and Brue. The Mendip Hills separate the Somerset Levels from the North Somerset Levels. The Somerset Levels consist of marine clay "levels" along the coast and inland peat-based "moors"; agriculturally, about 70 per cent is used as grassland and the rest is arable. Willow and teazel are grown commercially and peat is extracted.

A Palaeolithic flint tool found in West Sedgemoor is the earliest indication of human presence in the area. The Neolithic people exploited the reed swamps for their natural resources and started to construct wooden trackways, including the world's oldest known timber trackway, the Post Track, dating from about 3800 BC. The Levels were the location of the Glastonbury Lake Village as well as two Lake villages at Meare Lake. Several settlements and hill forts were built on the natural "islands" of slightly raised land, including Brent Knoll and Glastonbury. In the Roman period sea salt was extracted and a string of settlements were set up along the Polden Hills. The discovery at Shapwick of 9,238 silver Roman coins, known as the Shapwick Hoard, was the second-largest ever found from the time of the Roman Empire. A number of Saxon charters document the incorporation of areas of moor in estates. In 1685, the Battle of Sedgemoor was fought in the Bussex area of Westonzoyland at the conclusion of the Monmouth Rebellion.

As a result of the wetland nature of the Levels, the area contains a rich biodiversity of national and international importance. It supports a vast variety of plant and bird species and is an important feeding ground for birds and includes 32 Sites of Special Scientific Interest, of which 12 are also Special Protection Areas. The area has been extensively studied for its biodiversity and heritage, and has a growing tourism industry.

People have been draining the area since before Domesday Book. In the Middle Ages, the monasteries of Glastonbury, Athelney and Muchelney were responsible for much of the drainage. The artificial Huntspill River was constructed during the Second World War as a reservoir, although it also serves as a drainage channel. The Sowy River between the River Parrett and King's Sedgemoor Drain was completed in 1972; water levels are managed by the Levels internal drainage boards. During 2009 and 2010 proposals to build a series of electricity pylons by one of two routes between Hinkley Point and Avonmouth, to transmit electricity from the proposed Hinkley Point C nuclear power station, attracted local opposition. Discussions have taken place concerning the possibility of obtaining World Heritage Site status for the Somerset Levels as a "cultural landscape". It was suggested that if this bid were successful it could improve flood control, but only if wetland fens were created again; the plans were abandoned in 2010.

Natural character area

The Somerset Levels form a natural region that has been designated as a national character area – No. 142 – by Natural England, the public body responsible for England's natural environment. Neighbouring natural regions are: the Vale of Taunton and Quantock Fringes to the west, the Blackdowns to the southwest, the Mid Somerset Hills and Yeovil Scarplands to the southeast, the Mendip Hills to the east and the Bristol, Avon Valleys and Ridges to the northeast.

Geography

The Levels are mainly flat areas of inland plains and a coastal sand and clay barrier, east and west of the M5 motorway. There are some slightly raised parts, called "burtles", as well as higher ridges and hills. The Levels are about above mean sea level ( O.D.). The general elevation inland is O.D. with peak tides of O.D. recorded at Bridgwater and Burnham-on-Sea. Large areas of peat were laid down in the Brue Valley during the Quaternary period after the ice sheets melted. The area's topography consists of two basins mainly surrounded by hills, the runoff from which forms rivers that originally meandered across the plain but have now been controlled by embanking and clyses (the local name for a sluice). The area is prone to winter floods of fresh water and occasional salt water inundations. The worst in recorded history was the Bristol Channel floods of 1607, which resulted in the drowning of an estimated 2,000 or more people, houses and villages swept away, an estimated of farmland inundated, and livestock killed. Another severe flood occurred in 1872–1873, when over were underwater from October to March.

Although underlain by much older Triassic age formations that protrude to form what would once have been islands—such as Athelney, Brent Knoll, Burrow Mump and Glastonbury Tor—the lowland landscape was formed only during the last 10,000 years, following the end of the last ice age. Glastonbury Tor is composed of Upper Lias Sand. The Poldens and the Isle of Wedmore are composed of Blue Lias and Marl, while the Mendips are largely Carboniferous limestone. Although sea level changes since the Pliocene