46 Proceedings of the Royal Irish Academy. 



the southern end of the Threatening Gallery, in the opening leading into that 

 of the Elephants' Teeth, and at each end of the Bear's Den, left and right. 

 Such openings are characteristic of this section (Hyaena Land ), and plainly 

 conveyed the currents of streams that formed the galleries at a mur-h earlier 

 period than those swallow-holes and cross orifices found at the bottoms of 

 deep trenches (as in the Long Gallery and the Abyss), which point to a late 

 chapter in the cave's history, and which drained away the sand-bed in their 

 vicinr.v." 



8.— GEOLOGY. 



The remarks which follow are based on a personal examination of the cave 

 and surrounding district made on the occasion of several visits to Castlepook 

 in company with M whose loss, in common with all who had the 



pleasure of his acquaintance. I most deeply deplore. Only those, perhaps, 

 who day after day watched his ceaseless energy in the cave and the unvarying 

 enthusiasm with which he worked, in spite of conditions trying even to men 

 of half his age. can appreciate what an irreparable loss that particular branch 

 oi research in this country has sustained by his death. On several occasions 

 it was my privilege to help him by laying out the main lines of the survey on 

 which his beautiful plan of the cave was based. Those who have attempted 

 with an ordinary field theodolite to carry out a cave survey can realize the 

 severe physical discomforts involved in the process ; and not the smallest 

 share of these was borne by Mr. Usher, and in a manner that compelled 

 admiration, (in my la.-' dy a fern i*»fore his death, I spent 



three days running a series of levels round the whole ol the cave, in order to 

 determine the horizon ol the shelf and stalagmite floor. &o», and again he 

 gave me most material assistance, and toot copious notes from which numerous 

 cross-sections were drawn, some being here reproduced (see maj.i 



Oil' : the levelling was a source of great satisfaction to him as 



confirming a pre-conceived opinion that the main stalagmite floor developed 

 to a greater or less degree in the various passages in the cave was all on one 

 horizon, and belonged to the same period of fonnati >n. 



The cave is formed in vrr-ai is now a bluff or knoll of limestone of 

 Carboniferous Age, the Lower Limestone of the Geological Survey. A few 

 miles to the north are the Ballyhoura Mountains of Old Bed Sandstone Age, 

 rising to a height of some 1400 feet. 



A- - natty the case, the ca> -is of a number of passages formed 



by enlargement of the vertical cruse-joints of the rock. Those of one parallel 



