FLORIDA KEEPS. 33 
almost entirel}' of fragments of shells, but the fact that the same shell-con- 
glomerate occurs at Cape Sable, in the immediate prolongation of the south- 
ernmost shore bluff, convinces me that one and the same geological 
formation, identical in litliological character Avith the reef of Florida, and 
presenting only slight local modifications, extends all over the penin- 
sula of Florida, at least as far north as St. Augustine. Leaving this point, 
for the settlement of which we have not yet sufficient data, let us limit our 
comparison to the southernmost extremity of the peninsula and the keys. 
Here, at least, there can be no doubt that the southernmost shore bluff 
represents another range of keys similar to the main keys lying north of 
the mud flats, and that the Everglades within those bluffs are in reality 
another more extensive mud flat, agreeing in every respect with those lying 
between the main range of keys and the main-land. The only difference is 
that the Everglades have risen, with time, above the level of the sea. Were 
the present mud flats partially drained, or were a few additional feet of soil 
accumulated and consolidated upon them, their depressions would then cor- 
respond to the swampy ground, and their raised portions to the dry patches 
on the Everglades, while the Mangrove Islands would represent the hum- 
mocks. Nor does the agreement end here. About twenty miles from the 
southernmost shore, within the first prairies, another line of hummocks runs 
parallel with the first, and with the shore. This ridge, with an instinctive 
appreciation of its true character, has been called the Long Key. In short, 
these hummocks and Everglades represent as many ranges of kej's divided 
b}' mud flats, showing that the present keys and reefs of Florida are the 
last of a series of reefs advancing gradually from north to south, in a more 
or less concentric succession. Endeavoring to reconstruct this process, we 
should suppose that a long time ago, before the outer reef had grown up 
from its foundation, the present range of main keys was itself a growing 
reef, not yet reaching the surface. In the place of the mud flats now filling 
the space between the keys and the main-land was a channel as deep and 
imobstructed as that now lying between the main range of keys and the 
reef. Carrying the scene still farther back to an age for the duration of 
which we have no measure, the present shore bluffs are then the growing 
reef, rising to the surface here and there so as to form keys, while the south- 
ernmost part of the Everglades is changed to an ojDcn channel between the 
Long Key and the shore bluffs. Another backward step, and no reef rises 
between Cape Sable and Cape Florida, but the ocean beats against the Long 
