216 



MR. JUKES- imOWNE AND PROF. HARRISON 



yet mentioned. The matrix exhibited the usual debris of corals, 

 shells, nullipores, and polyzoa more or less cemented together by 

 lime. Near the surface the rock is ver^^ hard, but lower down it is 

 looser and less consolidated, being even friable in some places ; this 

 is doubtless due to the continual percolation of water through it, as 

 the quarr}^ is in the side of a large swallow-hole. Large corals 

 standing in the position of growth abound, some of them being 4 or 

 5 feet broad and 6 or 7 feet high, and where these are somewhat 

 weathered they look like huge decayed honeycombs. The}'' are, as 

 usual, merely casts, but here they certainly make up more than half 

 the mass of the rock. Shells also occur only in the form of casts, 

 species of Conus, Pecten^ Sjpondylus, and Pectunculus being recog- 

 nizable. The height of the ground here is 1050 feet. 



We are informed by those who have been concerned in sinking 

 wells in the higher parts of the island that the lower portions of the 

 rock are generally looser and more easily W'Orked than the upper, 

 and that sometimes the lowest portion resembles a mass of loose 

 rubble. As far as we can learn, big blocks or growths of coral are 

 most abundant on the outer slopes of the terraces, and large masses 

 are seldom found in the lower part of deep wells. 



Mr. E. C. Piggott, of Castle Grant, informs us that the well at 

 Ellis Castle, adjoining Nicholas-Abbey estate, cuts 150 feet through 

 coral, and he kindly sent us samples of the rock from 130 feet 

 down which were taken out in his presence. One of these was a 

 large lump of a compound coral, identified by Mr. J. W. Gregory (of 

 the British Museum, Natural Histoi j) -ds Heliastra^a crassilarnellata, 

 Duncan ; this is the greatest depth from which we have noted the 

 occurrence of a compound reef-coral. 



There are not many places in the island where the base of the 

 €oral-rock can be examined ; but one of these places is in Cole's 

 Cave, a cavern which opens into a deep gully on Walk's Spring 

 estate, and leads down into an underground watercourse which can 

 be explored for some distance. The limestone here rests directly 

 on the dark clays of the Scotland Series, its basement bed is loose and 

 rubbly, and in a distance of half a mile along the cavern only one 

 lump of coral, about a foot broad, was seen in it. 



In the same gully, about three quarters of a mile higher up, is 

 another cave, known as Harrison's Cave, and the coral-rock seen in 

 this is a calcareous sandstone consisting entire!}- of small debris 

 without any distinguishable corals for a distance of 300 or 400 

 yards from the mouth. The rock is, in fact, similar to the sand- 

 stone formed by the cementation of coral-beach sand, though it was 

 probably accumulated on a submarine sandbank. It rests here on 

 a white Eadiolarian earth. 



At Edgehill, about five miles north of Bridgetown, and at an 

 elevation of 450 feet, a well was recentlj^ sunk for the Water-Supply 

 Company. The coral-rock was found to be 100 feet thick, the first 

 50 feet being through the usual detrital rock without large corals ; 

 then from 50 to 60 feet there were large coral-masses, and below 

 this there were no corals, the material consisting of calcified coral- 



