NELSON ON THE BAHAMAS. 



207 



Fig. 2.— Vertical section of " jEolian" rock, from Mr. Burnside's 

 Quarry, Nassau, New Providence. Extreme height about 70 feet. 



Fig. 3. — Horizontal sec- 

 tion of " j3^olian" rock. 

 About 18 feet long. 



The largest and most instructive section 

 in the Bahamas of this calcareous sand- 

 stone is that in Mr. Burnside's Quarry, 

 at the end of the road in continuation of 

 Division Street, Nassau, across the hill 

 immediately under Fort Fincastle. The 

 stone is the ordinary "drip-stone" of the 

 Bahamas, and the structure is dome- 

 shaped, presenting, as usual in rocks of 

 ^olian origin, very irregular saddles on 

 every vertical section. See figs. 2 & 3. 



4. Lithological Notices. Ordinary 

 Rock, Chalk Mud, and Red Earth. — The 

 ordinary Bahama rock everywhere consists 

 of the above-mentioned calcareous sand- 

 stone. It is somewhat similar to Port- 

 land Stone in appearance, but softer and 

 more porous. When first exposed it is 

 quite white, and is inconveniently bright and dazzling under a 

 tropical sun ; but it becomes of a dark ashen grey colour along 

 the sea-coast, and more or less so elsewhere, when exposed to the 

 weather. Its average weight, like that of the Bermuda stone, va- 

 ries from 95 to 145 pounds per cubic foot. Its inferior value as a 

 building material arises from the numerous sand-flaws (specimen 

 No. 7), and consequent ready failure when exposed to the weather. 

 About the south-west of New Providence, for some feet above the 

 sea, the rock is hard and homogeneous, and may be raised in good 

 blocks for building purposes. The looser and softer kinds of rock 

 are found usually on the hill tops. A variety offering a singular 

 coimterfeit of true oolitic structure is found at or near White Cay, 

 Exuma, and elsewhere (specimens 4 & 9) ; but the spherules are 

 solid, and have been derived apparently from the stems of corallines 

 (see above, p. 206, and specimens Nos. 2 & 3). 



remarks, consist more of sand derived from shells than from corals ; whilst in the 

 Bahamas the reverse obtains. The hills, formed of these rocks, in the Bahamas 

 do not exceed 230 feet in height, in any instance ; in Bermuda they are not more 

 than 250 feet high ; in the islands of the Red Sea, however, they attain nearly 

 300 feet (as noticed by Ehrenberg). In the Pacific Islands the accumulation and 

 consolidation of the ^olian deposits appear to have made but little progress. 



