File:The Quarterly journal of the Geological Society of London (12511897835).jpg

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