ON THE MOVEMENTS OF UNDERGROUND WATERS OF CRAVEN. 347 



Many streams rise on the upper slopes of the hills and flow over the 

 Yoredales, but without exception their waters are swallowed directly 

 they pass on to the Carboniferous Limestone, to reappear as springs in 

 the valleys which trench the plateau. 



The Committee iirst turned its attention to tracing the water which 

 flows into Gaping Ghyll. 



It was generally believed that the water issued at a large spring 

 immediately above the bridge at Clapham Beck Head and immediately 

 below the entrance to Ingleborough Cavern. 



On April 28 specimens of the water from this spring were taken for 

 analysis before the introduction of any test. 



Two cwt. of ammonium sulphate was then put into the water flowing 

 into Gaping Ghyll, and at the same time the amount of the water was 

 gauged and found to be equivalent to 251,856 gallons per diem. A few 

 hours later a second quantity of two cwt. of the same substance was 

 introduced. 



On the same day H lb. of fluorescein in alkaline solution was put 

 into a pot-hole known as Long Kin East, about 1,300 yards north-east of 

 Gaping Ghyll. 



In view of the important influence which the direction of the joints in 

 the limestone had been found to exercise over the flow of underground 

 water, ^ the direction of the joints in the limestone clints in the neighbour- 

 hood of Long Kin East was taken, and was found to be N.N.W. to 

 S.S.E., and to run in such a direction as to lead to the probability that 

 the water would reappear at the springs at the head of Austwick Beck, 

 and these were consequently watched. 



The ammonium sulphate put in at Gaping Ghyll reappeared at the 

 large spring at Clapham Beck Head on the morning of May 3, and 

 continued to flow until the evening of May 6, when the water again 

 became normal. Thus the time occupied by the ammonium sulphate in 

 travelling from Gaping Ghyll to Clapham Beck Head, a distance of one 

 mile, was about five days. 



No ammonium sulphate was found in any of the other springs in 

 Clapdale. 



This result proved beyond doubt that Gaping Ghyll was connected 

 with Clapham Beck Head. 



The fluorescein put in at Long Kin East showed itself at Austwick 

 Beck Head, but not at any of the neighbouring springs, on May 11, having 

 taken over thirteen days to travel, the delay being probably due to the 

 small amount of water flowing at the time of the expei'iments. 



These results are of considerable importance, as they definitely reveal 

 two lines of divergent movement of these undergi'ound waters, and 

 indicate a subterranean watershed of much interest. The influence of 

 the master-joints of the Carboniferous Limestone in determining the 

 direction of flow of these underground waters was also, as at Malham, 

 clearly shown. 



The next set of experiments was carried out by the joint Committee 

 on June 8 and following days. 



In order to confirm the results in connection with the Gaping Ghyll 

 to Clapham Beck Head flow, and further to ascertain more definitely if 



> See previous investigations of the Yorks. Geol. and Poly. Soc. Committee. 



