TRANSACTIONS OF SECTION C. 735 



Towards the west the Carboniferous Limestone has been cut off by the Dent 

 Fault, while the Craven Faults determine its extension towards the south. The 

 main line of fault passes tliroug-h Ingieton, Olapham, and Austwiek to Settle, then 

 eastwards by Malliam. North of this is another fault, near the tirst at Austwiek, 

 but about H miles apart at Malhaui. Further north the most interestiu": caves 

 and pot-holes are found in an area comprising the Leek Fells, Kingsdale, Chapel- 

 le-Dale, Ribblesdale, and around Ingleborough. 



The whole area may be divided into three sections : 



1. The Yoredales, comprising the rocks of that name. These limestones being 

 comparatively thin, and intercalated with beds of shale and sandstone, the caves 

 are small and obstructed with earth, through which the watej- percolates. They 

 are at an elevation of from 1,300 to 1,000 feet, and do not materially aiiect the 

 drainage of the ground. 



2. The Southern Carboniferous, including the Carboniferous Limestone between 

 the two Craven Faults. Although part of the same formation as the Carboniferous 

 Limestone north of the Fault, yet the caves in the two section3 differ entirely in 

 their characteristics. Here they are distinguished by an absence of running water, 

 the walls are covered with a considerable thickness of calcareous deposit, and their 

 entrances are blocked with clay and rock di5bris. The well-known Victoria and 

 Attermire Caves are included in this section. A further characteristic is the 

 entire absence of pot-holes — vertical chasms in the ground caused by falling water 

 enlarging the rock fissures. 



3. The Main Carboniferous, which includes the remainder of the Carboniferous 

 Limestone within the ai-ea defined. Here there are no dry caves, all being active 

 drainage channels. Pot-holes also are very abundant. In the Leek Fell and 

 Kingsdale districts the caves are almost without exception those of engulfment, 

 while in Chapel-le-Dale and Piibblesdale they are cliiefly caves of debouchure. 

 The first-named are usually low at the entrance. The passages then increase in 

 height to 20 feet or more, but rarely exceed 6 feet in w'idth, usually much 

 narrower. Some may be traversed a quarter of a mile or more, such as Lost John's 

 Cave, which terminates in a subterranean pot-hole over 100 feet deep. The caves 

 of debouchure are much more numerous. The mouth is generally wide and 

 shallow, with a fiat roof. A cascade or waterfall is usually found some little 

 distance in, beyond which the passage is a simple water-worn channel, gradually 

 shallowing and broadening until too low to permit of further progress. 



The pot-holes occur at or near the top of the limestone, at between 1,100 and 

 1,300 feet elevation, and always where there are surface streams, which fall into 

 the chasms. Over thirty have been named, nearly all of which have been 

 descended by the writer and friends, members of the Yorkshire Kamblers' Club, 

 many of them for the first time. Half the number are over 100 feet deep. Gaping 

 Ghyll, on Ingleborough, attains a depth of 350 feet, and was first descended by 

 Mons. E. A. Jlartel in 1 895 Rowten Pot, in Kingsdale, was conquered in 1807, and 

 found to bn 365 feet deep, thus being the deepest known pot-hole in the country. 



No evidence of the presence of the Silurian rocks has been found, the lowest 

 observable rock being either light or black limestone. The average summer 

 temperature in both caves and pot-holes is 48° Fahr. 



The writer has prepared a special map of the district on which are shown all 

 the known caves and pot-holes, with the surface streams. Such a map illustrates 

 in a forcible manner the interesting fact that the entire surface drainage of 

 Ingleborough is swallowed up by the limestone. Not a single stream from the 

 higher levels continues an uninterrupted course into the valley below. 



5. The Underground Waters of North-West Yorkshire. By 'Rev. W. Lower 

 Carter, M.A., F.G.S., Hon. Sec. Underground Waters Committee, 

 Yorkshire Geological and PolytecJtnic Society, 



Part I. The Sources of the Aire. 



Introduction. Description of the area investigated. The Silurian and Car- 

 boniferous rocks between Malham Tarn and Malham are traversed by two 



