Prof. Horsford on the Rocks of the Florida Reefs. 2AM » 
- ; 
With the influx of the tide, the slopes become overspread with - 
the water and what it contains in suspension. The retreatin 
water, at ebb tide, leaves a thin layer of the animal matter, mix 
always when the water is agitated with the fine calcareous powder. 
Before the return of flood tide, exposure to the atmosphere and 
warmth have secured the succession of chemical changes enumer- 
ated above, and a thin layer of rock is formed. A repetition of 
this ‘process makes up the numerous excessively thin layers of 
which this rock is composed. ~ 
. On the ocean side the deposit is formed from spray, during 
winds which drive the froth of the sea, containing, with coral 
mud, the exuvie.from the barrier of living corals upon the low 
bluffs of the Keys.* 
Organic matter, 445 4:45 126 258 418 5°72 
Carbonic acid, 40: 39°64 41:08 270 3768 35°31 
Sulphuric acid,  0:0056 00056 — chidin  lt 
Lime, "ary a98 4635 46°80 — 5136 
Magnesia, sini, kc chal 623 «5:90 —_- — 
Water, | 367 3°30 a 559 «592 
9592 95:37 99°44 8 99°26 98°31 
fs and Islands in the 
details of the above 
ocess of aa 
¢ “In the first place, his (Prof. H.’s) paper only alludes to the rock formed above 
Be cor: nd-r A the 
low-tide level, which I have called t oral sand-rock. Again, amount of or- 
¢ matter in corals, as found by analysis, does not exceed five per cent. ; 
é san ich h liarly white and clear appear- 
the sands of the beach sae have a pecu anh they eontain is either un- 
tion among the 
i i a ann mand ion from me. 
ein Sena be er Souls be ‘yea in connection with the 
conclusions II, expressed at the end of my paper. zie E 
itici ld be just, if [had | 
In reply to the remainder of the paragraph, the criticism 2 ie nga yd orga 
any where ascribed the solidification, or any part of it, to any 
matter in corals. te: 
in the Proceedings of the Association, there — 
Since th blica tion al article f th 
have ped of i qu pypive heals of AS more important ingredients of the soft 
corresponding, aT conceive, with the rock 
rock, ‘ th of sub-aerial solidification in the 
Stoonp Sznizs, Vol, XIV, No. 41—Sept., 1852. 
