Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/166

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A little to the south-west of Redruth is a Tor, called Carn-brea or Karn-breh, with an old castle on the top. This hill forms a ridge extending from E.N.E. to W.S.W. and the highest point of it is six hundred and ninety-seven feet above the level of the sea. The northern side is covered with heaps of granite blocks, which are probably the debris of a part of the ridge. The rock appears to be of a very tender texture, and the water retained at the surface by the mould which covers it, contributes, no doubt, very powerfully to its decompositionq.

Carn Marth, another small hill, the summit of which is elevated eight hundred and forty-nine feet above the level of the sea, is distant two miles S.S.E. from Redruth. It is the highest point in the neighbourhood, and from it may be seen the two channels and the port of Falmouth, which is about seven miles distant in a straight line. The upper part of Carn Marth (about one-third) is granite; large blocks are strewed over this part of the mountain, and they appear to have been rolled from the summit. In general, all these