The Somerset Uplands
The Northern Uplands
The northern uplands of Somerset occupy the area between the River Avon in the north and the Axe Valley. The ulands consist of the Mendip Hills as well as Landsdown, Langridge and Solsbury Hills to the north of Bath - these last three are actually outliers of the Cotswold Hills to the east. They also include Bleadon Hill, Brean Down and Steep Holm in the Bristol Channel.
The Southern Uplands
The area between Penselwood and the Blackdown Hills make up the Southern Uplands of Somerset. Apart from the significant limestone hill of Ham Hill with its attendant fossils, the area is quite complex geologically. The Blackdown Hills run southwest into Devon and consist of Upper Greensand - a greenish sandstone laid down in a shallow marine environment and dating from the Early Cretaceous period.
The Quantock Hills
The Quantocks are basically a twelve mile long ridge of Devonian slates and sandstones running between Watchet in the north to Taunton in the south.
The Polden Hills
The Polden Hills bisect the Somerset Levels an are a low range of hills running for 10 miles between Puriton in the west and Street in the east. They consist of Blue Lias banded with clay and date from the Jurassic and Triassic geological perioods. They trend approximately parallel to the Mendips and it is thought as many as 30 ancient timber trackways, similar to the famous Sweet Track, once connected the Polden Hills to settlements at Meare and Edington Burtle.
Situated in the far west of Somerset and bordering the county of Devon, Exmoor is an upland area of sedimentary rocks classified as gritstones, sandstones, slate, shale and limestone, siltstones, and mudstones. They date from the Devonian and early Carboniferous periods and sue to the fact that this area of Britain did not experience glaciation, the moorland plateau remains a remarkably old landform.
The total area of the Exmoor National Park is 267.5 square miles (693 km2), of which 71% is in Somerset and 29% in Devon. The highest point on Exmoor is Dunkery Beacon; at 1,703 feet (519 m), it is also the highest point in Somerset. Exmoor has 34 miles (55 km) of coastline, including the highest sea cliffs in England, which reach a height of 1,030 feet (314 m) at Culbone Hill. However, the crest of this coastal ridge of hills is more than 1 mile (1.6 km) from the sea. The western extremity of Exmoor is the 820ft (250m) high Little Hangman near Combe Martin, Devon.
The Brendon Hills
The Brendon Hills are basically an outlier of Exmoor and are separated from it by the valley of the river Avill. The highest point on the Brendon Hills is Lype Hill at 1,385ft (422m) such island was the Isle of Athelney, fortified by King Alfred the Great prior to the battle of Ethandun against the Danes in May 878. Ten years later King Alfred arranged for the building of Athelney Abbey, a monastery that stood for over six hundred years until the Dissolution of the Monasteries in 1539 under the orders of King Henry VIII.