Tor

:This article is about a kind of hill. For articles about other uses of "tor", see Tor (disambiguation).

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A tor is a large hill, usually topped with rocks. The term is most commonly used in the South West of England - particularly with reference to the high points of Dartmoor, in Devon.

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Dartmoor represents one of the largest areas of exposed granite in the United Kingdom, covering an area of 241 square miles (625 square kilometres) (source: Dartmoor National Park). It is part of a chain of granite stretching through Cornwall, as far as the Isles of Scilly.

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Its tors are the result of millions of years of erosion. In prehistoric times, when the land was covered in forest, rain water seeped into the ground and gradually eroded the bedrock through its natural cracks, or joints. Once the land became exposed, the erosion was accelerated, particularly during the Ice Age when freezing water expanded in the cracks. The result can be seen today in dramatic rock formations.

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Some of the more durable granite survived to form the rocky crowns of Dartmoor tors. One of the best known is at Hay Tor, on the eastern part of the moor, whose granite is of unusually fine quality and was quarried during the 19th and early 20th centuries. Its stone was used to construct the pillars outside the British Museum in London, and to build London Bridge (now in Arizona). The last granite to be quarried there was used to build Exeter War Memorial in 1919.

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Weathering has also given rise to circular ?rock basins?, formed by the accumulation of water and the repeated freezing and thawing - a fine example is to be found at Kes Tor.

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As the erosion of the tors continues, the rock is broken down into ever smaller sizes. Many hillsides are covered with loose rocks, known as clitter, which have provided ready building materials for thousands of years. Eventually the granite is eroded down to a level equivalent to sandy gravel - known as growan, which consists of individual crystals.

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Ten Tors is an annual weekend hike on Dartmoor.

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Hill: For the landform that extends less than 600 metres above the surrounding terrain and that is smaller than a mountain, see the mountain article. Many hills are taller than most skyscrapers but are generally small....

South West: redirectSouthwest...

England: :For an explanation of often confusing terms like England, (Great) Britain and United Kingdom see British Isles (terminology)....

Tor related Images and Photos (experimental)

Glastonbery Tor	Glastonbury Tor Glastonbury Somerset England UK	High Tor Matlock Derbyshire 1756	Glastonbury Abbey with the Tor Beyond
River Brue with Glastonbury Tor in the Distance Somerset England United Kingdom	Reflection of Clouds in the River River Brue Glastonbury Tor Glastonbury Somerset England