~ On the Gulf Stream and the Keys of Florida, 49 
fore, that the line ad’, marks the position of a former reef changed 
into keys by the action of waves alone. : 
It has been pointed out by Tuomey, and proved by Agassiz, 
that in a similar manner, the southern coast of Florida was the 
position of still another and earlier reef. The character of the 
rock is the same as that of the keys of the main range, or of the 
smaller ones on the living reef. Here also Tuomey has seen, as 
he supposes, the evidence of elevatory forces, while Agassiz sees 
nothing but the action of the waves. 
here seems to be no reasonable doubt, therefore, that at some 
former period, the northern shore of the everglades was the posi- 
tion of the southern coast, and at the same time the present south- 
ern coast was the position of a reef. The general sequence of 
changes has been as follows: The reef ab became gradually 
converted into a line of keys, and was finally added to the main- 
land, and the shoal water became the everglades, and its mangrove 
islands, the hammocks which overdot this swamp. In the mean- 
time, that is, while the present southern coast was still a line of 
keys, another reef was formed farther out. This became in time 
@ similar origin for that portion of the peninsula lying north of 
this line is less*abundant, and perhaps less conel ve, and yet 
we have every reason to believe that the greater portion of this 
t to - Agassiz from the shores of Lake George 
and other parts of Florida as far north as St. Augustine, leave 
that on the eastern coast at least the coral formation ex- 
ds as far north as that ancient city. I have myself a frag- 
ment of Meandrina from the neighborhood of St. Augustine, un- 
distinguishable from fragments which may be picked up any- 
SECOND SERIES, VOL, XXIII, NO. 67.—JAN., 1567. 
7 : 
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