32 



MH. H. DYKE ACLAKD ON A 



[Feb. 1904, 



section (PI. VI, fig. 1), to the depth of 15 feet. Below is a rough 

 drawing of a section of it (fig. 2). 



Beneath the stalagmite-floor, which varied in thickness from a 

 few inches to a foot or more, was a layer of fine calcareous sand. 

 Then came coarser sand, and then rubble down to the depth of 11 

 feet. Embedded in the coarse sand and rubble were angular and 

 subangular boulders of limestone, some of large size. A complete 

 change then took place, and there came a bed of hard calcareous 

 grit, the coarse grains of sand, small pebbles, fragments of shells, 

 and small stalactites being cemented together by some material 

 closely resembling stalagmite. This bed was several inches thick 



Fig. 2. — Section of the floor in the cave at Monkey's Quarry, 



Gibraltar. * 



Stalagmite 





Fine Calcareous Sand 



Coarse Calcareous Sand 



,. 'i>_ _ "_ ... _Rock - Floor- _l_ - — 





5 Calcareous Grit 

 Stones bored bv Eholades, 



: Echinids & barnacles- 



where it lay between the boulders. In it and below it were numerous 

 well-rounded stones, some of them pierced by Pholas. There 

 were also a few scattered chips of angular limestone. At 13 feet 

 I found echinids and barnacles. 



The shaft was sunk down the side of the cave, which was 

 smooth and waterworn, and in places there were holes apparently 

 bored by Pholas. At 15 feet the side sloped inward rapidly 

 towards the centre of the gallery, and the bottom of the shaft was 

 solid rock. I have no doubt that this is the original floor of the 

 cave. At this point, therefore, it is about 2 feet above sea-level. 

 There were a few inches of fresh water at the bottom, and although 



