78 Notices of Memoirs — C. B. Wedd — CoralUan Limestones. 



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 Ribblesdale they are chiefly 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 G feet in 

 width, 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 flat 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 Monsieur E. A. Martel, in 1895. Rowten Pot, in Kingsdale, 

 was conquered in 1897, and found to be 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 whicb 

 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. 



IV. — The Outcrop of the Corallian Limestones of Elswoeth 



AND St. Ives.^ By C. B. Wedd, B.A., F.G.S. 



(Communicated by permission of tlie Director-General of the Geological Survey.) 



THE ferruginous and oolitic limestones known as the Elsworth 

 and St. Ives Rocks are now generally believed to be one and 

 the same, an opinion supported by my own work in that district 

 recently. The limestone in question has long been known to occur 

 at St. Ives in brick-pits, being well exposed to the west of the town. 

 It was known also to occur throughout the village of Elsworth. 

 Mr. Cameron noticed a fossiliferous rock outcropping near Hilton, 

 between Elsworth and St. Ives. No other surface exposures were 

 known, but a similar rock was found in the railway cutting at 

 Bluntisbam, north-east of St. Ives, at Swavesey, east of the same 



* Read before the British Association, Section C (Geology), Bradford, Sept., 1900. 



