TORS OF DARTMOOR
a database of both lesser- & well-known rocks and outcrops
Two Bridges Quarry Tor This is an interesting cliff face of rock, situated in the old quarry now used as a car park for Wistman's Wood, opposite the Two Bridges Hotel. So named by Sanders and Watson (1996), the extract reads: "This small tor-like outcrop has been exposed in Two Bridges Quarry. The structure of this buried tor supports Linton's theory of Tor formation by weathering before exposure to the atmosphere." Tim Jenkinson and Ken Ringwood also, later on, mention this phenomenon, the latter showing a photograph in his book on Dartmoor Tors.  Linton is credited for his work by Devon.Gov.UK; "Two Bridges Quarry is one of the most important geomorphological sites in south-west England, particularly noted for its association with D. L. Linton and his classic theory of tor formation. The site shows heavily decomposed granite juxtaposed with a mass of relatively more sound bedrock. The classic nature of the site and its historical significance in development of ideas on tor genesis in Britain is apparent from the numerous references to the site in the geomorphological literature. Two fine grained granite dykes cross the weathered granite face."  Also, in the "Detailed Geology" section; "It is one of the best used localities for demonstrating proposed mechanisms for granite decomposition including chemical weathering, pneumatolytic alteration as well as physical disintegration and weathering. The latest evidence from the site is probably the most convincing and suggests that the weathering of the Dartmoor granite was selective and that it probably occurred under a warm and mildly humid climate. Major difficulties still remain, however, in assessing the relative effects of hydrothermal alteration and chemical weathering where they occur together in one section, a situation believed by some to occur at Two Bridges Quarry." A rather debatable outcrop to add to the list since, were it not for the small quarry, it would not be visible and thus not entirely a natural feature. But, we feel it is significant enough to be included and is worth a visit. 
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