62 Remarks upon East Florida. 
closely joined, like that superimposed. A thin stratum of sand 
next succeeds; and then a third stratum of shelly rock, about 
two feet and a half thick, the component parts of which are ina 
state rather more comminuted than any lying above. ‘This stra- 
tum is likewise of a more solid and uniform character than its as- 
sociates, and gives the largest blocks for building purposes. A 
sandy stratum is found below this, and, so far as an examination 
has penetrated, the coquina formation descends no lower. 
_ All these strata are firm concretions, their component parts being 
obviously conglutinated by a caleareous substance, which holds 
them well together. This foreign substance, or cement, is quite 
visible in the finer formations, though little seen in the coarser 
Taking up a piece of the latter, the cause of cohesion is appa- 
rently so slight, that one is eapeiene that the mass does not crum- 
ble at a touch. 
It is a common conjecture that the coquina is of recent forma- 
tion, and that causes are still operating to produce it. This 
conjecture has some apparent and plausible grounds. It wants, 
however, the support of deeper investigation into the character 
and force of these causes. Fragments have been constantly 
heaping up on the coast, portions of which have been long lying 
in a quiescent state, without exhibiting any evidences of a change, 
or a \ tendency to.one, particularly of a change from a loose toa 
state. The upper stratum of the quarries we have been 
desc would be likely to assume the character of the strata 
below, if such a change were in progress. But the century du- 
ring which it has been subject to observation, has witnessed no 
alteration. 'The fragments all lie in.a ee state, without 
showing any signs of cohesion. 
t has been surmised, that the animal matter of the shells 
might have furnished the element of cohesion. But this surmise 
would seem to be at once disproved by the condition in which the 
shells were found, when the concretion took place. It is evident 
that they must have been subjected to a long and severe process 
of attrition and contusion; previous to that event; such a process 
as must have widely separated all animal matter, from its former 
3 covering. Besides, there is no reason for supposing, that this an- 
matter, even if it had existed in connection with the shells at 
inane the ae | formation pocurred, could have ome the 
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