34 ON RAINS CAVE, LONGCLIFFE, DERBYSHIRE. 



The antiquity of the cave must be immense. As many readers of 

 this article will not be familiar with geology^ a brief digression into 

 the formation of the caves of limestone districts is pardonable. 

 Limestone caves are wholly, at first, and in a great measure in their 

 later career as living caves, due to chemical action. Rain water, in 

 its passage through the atmosphere, absorbs carbonic acid gas, and 

 still more so in sinking through the decomposing vegetable matters of 

 the upper soil. Water charged with this gas has the power of 

 dissolving carbonate of lime of which limestone rocks are mainly 

 built up. That this does take place is forcibly proved by the 

 encrustations of petrifying wells, the banks of tufa and the 

 stalagmites of limestone districts — all of which are due to the 

 precipitation of dissolved rock in the water. The " fur " of 

 kettles is another example. But such charged water cannot dissolve 

 an unlimited quantity of rock — the work done in this line depending 

 upon its richness in the gas. Hence the cracks and joints of 

 the rock out of which the future cave is to develop, must have 

 their sides eaten away by moving water ; else, if the water ate and 

 was satisfied, no more rock would be eaten. But water, like human 

 beings, will not choose a devious and difficult way (as these under- 

 ground crevices) in preference to an easy one (as by brook or river), 

 unless there is something to be gained. The only reason water can 

 have in choosing a difficult underground course is to reach a lower 

 level by a " short cut." But once grant this ; if the supply be plenti- 

 ful, the cracks will in due time become caves and the trickle a torrent. 



There is an excellent example to the point near Castleton. Westward 

 of the Winyates is a trough-like valley, about three miles long, by 

 the side of which is the Chapel-en-le-Frith road. This valley is 

 entirely drained by ''water-swallows" — natural drains along the 

 bottom, through which the surface-rills sink out of sight. Under- 

 ground these waters collect, and at length emerge at a much lower 

 level as the Russet Spring near Peak Cavern, and then become the 

 sparkling brook which runs through Castleton. The ancient surface 

 outlet of this valley, by which its waters were originally turned into 

 the Wye (instead of the Noe as at present), is still visible, although 

 high and dry, leading towards Peak Forest. 



