"This great northern bog, divided into two sections by Fur Tor and Fur Tor Cut, extends southwards to within a short distance of Great Mis Tor, and is a vast receptacle of rain, which it safely holds throughout the driest summer. Fur Tor Cut is a passage between the north and south parts of this great bog, evidently cut artificially for a pass for cattle and men on horseback from Tay Head, or Tavy Head, to East Dart Head, forming a pass from west to east over the very wildest part of Dartmoor. Anyone can walk over the bogs; there is no danger or difficulty to a man on foot unless he gets exhausted, as some have done. But horses, bullocks, and sheep cannot cross them. A man on horseback must take care where he goes, and this Fur Tor Cut is for his accommodation."[1] The Fur Tor Mire is not composed of black but of a horrible yellow slime. There is no peat in it, and to cross it one must leap from one tuft of coarse grass to another. The "mires" are formed in basins of the granite, which were originally lakes or tarns, and into which no streams fall bringing down detritus. They are slowly and surely filling with vegetable matter, water-weeds that rot and sink, and as this vegetable matter accumulates it contracts the area of the water surface. In the rear of the long sedge grass or bogbean creeps the heather, and a completely choked-up mire eventuates in a peat bog. Granite has a tendency to form saucer-like depressions. In the Bairischer Wald, the range dividing Bavaria from Bohemia, are a number of picturesque tarns, that look as though they occupied the craters of extinct volcanoes. This, however, is not the case; the rock is granite, but in this case the lakes are so deep that they have not as yet been filled with vegetable deposit. On the Cornish moors is Dosmare Pool. This is a genuine instance of the lake in a granitic district. In Redmoor, near Fox Tor, on the same moors, we have a similar saucer, with a granitic lip, over which it discharges its superfluous water, but it is already so much choked with vegetable growth as to have become a mire. Ten thousand years hence it will be a great peat bog.