212 



ME. JITKES-BKOWNE AND PROF. HARRISON 



higher plateau, and this thick- 

 ness is probably all coral- 

 rock (see fig. 6). 



Farther north a boring was 

 made in the gully which runs 

 between Mount Brevitor and 

 Pleasant Hall, at a spot which 

 is about 80 feet below the 

 surface of the ground near 



the edge 



the 



of the gullj^ ; 

 boring was carried through 

 coral-rock, going through a 

 cave at 116 feet and the base 

 of the coral at 130 feet : the 

 total thickness of the rock at 

 this place appears therefore 

 to be at least 210 feet. 



Lastly, we ascertained that 

 the well at Nicholas Abbey, 

 near Mount Stepnej^, is 170 

 feet deep, and Avas dug en- 

 tirely through coral, the water 

 at the bottom being probably 

 held up by the Scotland clays 

 which crop out below Mount 

 Stepney. 



(c) Internal Structure of 

 the Coral-roclc. — Excellent 

 opportunities of examining 

 the coral -limestones are 

 afforded by the cliffs on the 

 southern coast, by the nume- 

 rous quarries and road- 

 cuttings, and by some of the 

 steep slopes where the rock 

 is bare and weathered. 



The rock varies consider- 

 ably in structure and in 

 hardness even on the same 

 level or terrace, but its usual 

 character at levels below 300 

 feet is that of a rough whitish 

 coarse-grained limestone, suf- 

 ficiently compacted to stand 

 in cuttings and quarries with 

 a vertical face, but so little 

 indurated that it can often 

 be cut with a saw. Some 

 portions of it are so ^oft, 

 loose, and earthj?^ that they 

 can be dug out with a spade. 



