Devon - Geography and Geology

Geography and Geology

A sharp geological dividing line cuts across Devon roughly to the west of Tiverton and Exeter and ending around Newton Abbot and Torquay. This forms part of the Tees/Exe line dividing Britain from the lowlands (sedimentary rocks) that are predominant to the east of the line and the higher land (igneous and metamorphic rocks) which dominates to the west.

The principal geological formations of Devon are the Devonian (in north Devon, south west Devon and extending into Cornwall); the Culm Measures (north western Devon also extending into north Cornwall); and the granite intrusion of Dartmoor in central Devon, part of the Cornubian batholith. There are small remains of pre-Devonian rocks on the south Devon coast.

Devon gave its name to a geological period: the Devonian period, so named because of the abundance of the grey limestone found there. It was Roderick Murchison and Adam Sedgwick who originally named the Devonian Period following research they carried out in Devon, and in particular, Torbay. They found some unusual marine fossils in the limestone at Lummaton Quarry and it was this discovery that led to the time period becoming known globally as the Devonian.

Devon's second major rock system is the Culm Measures, a geological formation of the Carboniferous period that occurs principally in Devon and Cornwall. The measures are so called either from the occasional presence of a soft, sooty coal, which is known in Devon as culm, or from the contortions commonly found in the beds. This formation stretches from Bideford to Bude in Cornwall, and contributes to a gentler, greener, more rounded landscape. It is also found on the western, north and eastern borders of Dartmoor.

The whole of central Devon is occupied by the largest area of igneous rock in South West England, Dartmoor.

The sedimentary rocks in more eastern parts of the county include Permian and Triassic sandstones (giving rise to Devon's well known fertile red soils); Bunter pebble beds around Budleigh Salterton and Woodbury Common and Jurassic rocks in the easternmost parts of Devon. Smaller deposits of even newer rocks also exist, such as Cretaceous chalk cliffs at Beer head and gravels on Haldon, plus Eocene and Oligocene ball clay and lignite deposits in the Bovey Basin, formed around 50m years ago under tropical forest conditions.

Devon is the only county in England to have two separate coastlines; the South West Coast Path runs along the entire length of both, around 65% of which is named as Heritage Coast. Devon has more mileage of road than any other county in England: before the changes to counties in 1974 it was the largest by area of the counties not divided into two or three parts. (Its acreage was until 1974 1,658,288: only exceeded by the West Riding of Yorkshire.) The islands of Lundy and Eddystone are also in Devon.

Inland, the Dartmoor National Park lies wholly in Devon, and the Exmoor National Park lies in both Devon and Somerset. Apart from these areas of high moorland the county has attractive rolling rural scenery and villages with thatched cob cottages. All these features make Devon a popular holiday destination.

In South Devon the landscape consists of rolling hills dotted with small towns, such as Dartmouth, Ivybridge, Kingsbridge, Salcombe, and Totnes. The towns of Torquay and Paignton are the principal seaside resorts on the south coast. East Devon has the first seaside resort to be developed in the county, Exmouth and the more upmarket Georgian town of Sidmouth, headquarters of the East Devon District Council. Exmouth marks the western end of the Jurassic Coast World Heritage Site. Another notable feature is the coastal railway line between Newton Abbot and the Exe Estuary: the red sandstone cliffs and sea views are very dramatic and in the resorts railway line and beaches are very near.

North Devon is very rural with few major towns except Barnstaple, Great Torrington, Bideford and Ilfracombe. Devon's Exmoor coast has the highest cliffs in southern Britain, culminating in the Great Hangman, a 318 m (1,043 ft) "hog's-back" hill with an 250 m (820 ft) cliff-face, located near Combe Martin Bay. Its sister cliff is the 218 m (715 ft) Little Hangman, which marks the western edge of coastal Exmoor. One of the features of the North Devon coast is that Bideford Bay and the Hartland Point peninsula are both west-facing, Atlantic facing coastlines; so that a combination of an off-shore (east) wind and an Atlantic swell produce excellent surfing conditions. The beaches of Bideford Bay (Woolacombe, Saunton, Westward Ho! and Croyde), along with parts of North Cornwall and South Wales, are the main centres of surfing in Britain.