H. C. Sorby — On the Excavation of Deep Dale. 347 



might be used to make the pieces fit — the result may look very well, 

 but it will leave us no wiser as to the natural history of the rocks. 



I may mention that the paper on some Alpine and Himalayan 

 sections, which I had the honour to lay before the Geological Society 

 two years ago,^ bears upon the question here discussed : there is 

 said to be a fissure along the base of the Alps, currently sup- 

 posed to have swallowed up mountain ridges, and at sundry times 

 to have given egress to the whole mass of the Alps ; yet no one has 

 given a circumstantial description of so wonderful a feature. If 

 such a fissure can hide away and tell us nothing of such mighty 

 performances, there will be, to my mind, a greater flaw in the 

 geological record than any yet proved from palgeontology. 



III. — Note on the Excavation of the Valleys in Derbyshiee. 

 Ey H. C. Sorby, F.R.S., &c. 



FOE a considerable time I have taken much interest in the question 

 of the origin of the narrow and deep valleys in the Carboni- 

 ferous Limestone district of Derbyshire, and have cai-efully recorded 

 whatever seemed to explain their formation. So far I have never 

 met with more striking facts than those to be seen in Deep Dale, 

 about three miles in a direct line E.S.E. from Buxton. I estimate 

 the depth of the valley at about 100 feet, and its width at from 100 

 to 200 yards. At a distance of about a mile from the Bakewell road 

 there is a cavern, which is especially conspicuous on the east side. 

 Its entrance is about 6 feet high, 20 feet broad, and 40 feet above the 

 bottom of the valley. It extends nearly horizontally for about 30 

 yards, and then descends to a lower level, where I did not further 

 examine it. On looking from the entrance to the opposite side of 

 the dale I was surprised to see what appears to be a continuation of 

 the same cavern. The entrance on that side is at about 80 feet above 

 the valley, and is so much blocked up with detritus that one can 

 only examine it for a space of 10 yards. Taking, however, all the 

 facts into consideration, it appears to me that at a very remote 

 period a subterranean stream flowed continuously along these two 

 caverns, from west to east. There is abundance of suitable gather 

 ground on the west side which even now has no well-marked surface 

 drainage, and from which much of the water probably escapes by a 

 subterranean comse, ending in the large spring in the main valley, 

 by the road-side below Kingsterndale. Of course the continuous 

 passage of a stream through the two portions of the cavern could 

 not possibly occur in the present state of Deep Dale — the water 

 would have to run down one side of the valley, and up a steep in- 

 cline on the other, and, therefore, I argue that at the time when the 

 cavern was the bed of a subterranean stream, Deep Dale was ouly 

 excavated to a slight extent. In the process of time, however, its 

 depth was so increased that the cavern was cut in two ; and a 



1 Read June 5tli, 1867. Published in the Quart. Jom-u, Geol. Soc, London, 1868, 

 Vol. xxiv., p. 34. 



