30 3IR. H. DYKE ACLAND ON A [Feb. I904, 



3. On a Xew Cave oa the Eastern Side of Gibraltar. By 



Henry Dyke Aclaxd, Esq., F.G.S. (liead November 4th, 



1903.) 



[Plate VI — Plan & Sections.] 



A new cave was discovered on the eastern side of Gibraltar 

 on August loth, 1902. It is situated a short distance south of 

 the eastern end of the tunnel which pierces the Rock, from the 

 Dockyard on the western side to ' Monkey's Quarry ' on the 

 eastern. Blasting and quarrying operations are being carried on 

 in the quarry, to procure material for the new dockyard. An 

 explosion is said to have blown in the face of the limestone-cliff, 

 and a small hole was discovered ; when this was entered, it was 

 found that it led into a cave of considerable dimensions. I have 

 not been able to determine whether the hole w r as made in the 

 ' massif,' or whether the explosion merely blew away the rubble and 

 breccia that forms the talus of the cliff, thereby uncovering an old 

 entrance. Further quarrying operations have so enlarged the opening 

 that none of the original cliff-face remains very near it. I am told 

 by Mr. A. K. Peaty, Assistant Civil Engineer, that he saw the 

 opening two hours after it had been made, and that, in his opinion, 

 the hole had been pierced through the massif, and was not a re- 

 opening of the old entrance. In any case, it must have been very 

 near an old entrance, as a glance at PI. VI, fig. 1 shows that 

 the stalagmite-floor slopes up to within a few feet of the present 

 opening, and the sides of the cave, so far as they can be seen through 

 the accumulation of fallen rock, clearly indicate that an old entrance 

 was very close at hand. Moreover, this stalagmitic floor does not 

 rest upon the solid rock, but upon a mass of breccia of unknown 

 thickness ; and it seems probable that, if this were removed, the 

 original floor of the cave would be found at a much lower level. 



It' may be desirable to describe, first of all, the situation of the 

 cave and its general features, and then to point out some of the 

 interesting problems which it presents. 



Fig. 1 (p. 31) shows that the cliff comes down at this place to a 

 platform formed by the quarrying away of the talus, 64 feet above 

 sea-level. The cliff consists of massive limestone, in which no 

 bedding can be detected. There is a small fault to the south of the 

 entrance to the cave, and this probably forms one side of the cave 

 itself. The talus consists of coarse rubble, resting upon similar 

 material of more ancient date which is now consolidated into a 

 breccia. This platform was covered, before the quarrying began, to 

 a large extent with roughly-stratified fine and coarse rubble, similar 

 to that which still remains in situ immediately south of the tunnel. 



The present entrance to the cave is 24 feet above the platform, 

 and 88 feet above sea-level. On entering the cave, a fine view is 



