FLORIDA REEFS. 13 
We cannot therefore infer from the absence of organized beings in ancient 
formations of this character, that they were deposited in a pehigic sea, des- 
titute of life. This has ah'eady been pointed out by Mr. Dana,* in his Report 
on the Coral Reefs of the Pacific. It must not, however, be supposed that 
organic remains are wholly wanting in coral formations. There are, on the 
contrary, localities whei'e they are found in considerable numbers. In such 
cases the action of the sea has probably been less violent, or in some 
instances shells may have accumulated in such quantity, before being 
cemented together, as to offer a certain resistance to destructive influences. 
Occasionally also, delicate shells or sea-urchins may be lodged in the cavities 
of coral stems, afterwards filled in with sand, and thus protected. 
We see everywhere that the larger boulders and the coarser fragments 
have been the first to find a resting-place upon the dead reef; the minuter 
particles and coral sand, which are periodically washed away from its crest 
during heavy gales, never accumulating upon it till large boulders and 
more solid materials have collected to such an extent as to form sufficient 
protection for the more movable looser fragments. This fact is beautifully 
illustrated by an accurate survey of Sand Key, where a wide field of large 
boulders is partially laid bare at low water, jjresenting the appearance of an 
extensive key, Avith a low hill of minute materials, the product of some 
heavy gale, heaped upon the summit, against which the sea plays without 
disturbing it materially, even at high water, when it leaves in sight only 
a nucleus, as it were, for a greater accumulation of such loose materials 
Avhich may in time cover the whole surface of the larger boulders. We 
have here in reality the same phenomenon which is observed upon all 
beaches, where larger materials have first accumulated on a shoal shore, 
being followed, in the course of time, by more minute fragments which have 
found a resting-place upon levels where the sea was powerless to increase 
the collection of coarser matter. In attempting to imderstand these forma- 
tions, it must be remembered that the accumulation of the larger materials, 
collected at a certain level, may modify the action of the Avater at a sub- 
sequent period, thus producing a combination of substances, heaped uncon- 
formably upon each other. This is, in reality, the case throughout the 
Avhole main range of keys, which have been raised to their present level 
by the action of the tides and gales for ages past; the fragments of which 
they are composed having been thrown up at different periods, and over- 
* Geology of the United States Exiiloriug Expedition. 
