74 Notices of Memoirs — Underground Waters of Craven. 



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 Com- 

 mittee on June 8 and following days. 



In order to confirm the results in connection with the Gaping 

 Ghyll to Claphara Beck Head flow, and further to ascertain moro 

 definitely if there existed any connection between Gaping Ghyll 

 and the smaller springs in Clapdale, 10 cvvt. of common salt was 

 put into the waters of Gaping Ghyll on June 4, and a further 10 cwt. 

 on June 5, samples of the water from each of the springs being 

 taken several times a day until June 25. 



One pound of fluorescein in alkaline solution was introduced into 

 the stream flowing through Ingleborough Cave on June 8 at 10 p.m.^ 

 at the point where the water plunges down a hole in the floor of the 

 cave, and marked ' Abyss ' in the 6-inch Ordnance map. Five cwt. 

 of ammonium sulphate was introduced into a sink on the allotment, 

 about 500 yards north-east of Long Kin East, on June 9, at 3 p.m. ; 

 and at 3*15 p.m. on the same day 1 lb. of fluorescein in alkaline 

 solution was poured into the stream which flows past the shooting- 

 box on the allotment and sinks near the Bench Mark 13201. 



The fluorescein introduced into the abyss came out of Claphami 

 Beck Head, and possibly at Moses Well and other springs ia 

 Clapdale, but this point requires further investigation, the evidence 

 being as yet somewhat unsatisfactory. The salt from Gaping Ghyll 

 appeared at Clapham Beck Head on June 15, 16, 17, 18, 19, 20, and 

 21, being at its maximum on June 18, but not at any of the other 

 springs. 



The ammonium sulphate put into the sink on the allotment 

 appeared at Austwick Beck Head on June 22, the other springs ia 

 the neighbourhood being unafifected on that day ; but on the 24th 

 and 25th there were slight increases in the amount of ammonia in 

 two small springs in Clapdale, viz., the small spring below Clapdale 

 Farm and Cat Hole Sike. As one of these streams is close to the 

 farmyard, and the other was at the time nearly dry and flowing 

 through pasture land, no importance is attached to these slight 

 increases. Of the fluorescein put in below the shooting-box no 

 trace has since been found, and the same is the case with ^ lb. of 

 methylene blue introduced into Grey Wife Sike, above Newby Cote. 



Several most interesting problems still await solution in this area, 

 one of them being the relations of the Silurian floor which underlies^ 

 the Carboniferous Limestone of the plateau to the flow of under- 

 ground water. The two sinks Gaping Ghyll and Long Kin East 

 are only about 1,300 yards apart, and yet the waters of the one take 

 a direction quite distinct from those of the other, and eventually 

 emerge in a separate valley, the distance between the springs being 

 1^ miles apart, the great mass of Carboniferous Limestone known as 

 Norber, a hill upwards of 1,300 feet in height, lying between the 

 two valleys. In Crummack Dale it is seen that the Silurian rock» 



