. Elements of geology : a text-book for colleges and for the general reader. Geology. REEFS OF FLORIDA. 157 with its reefs and keys, and Fig. 128 is a section along the line N S. The southern coast (a a) is ridge, elevated twelve to fifteen feet above the sea-level, within which is the Everglades (e) an extensive fresh- water swamp only two or three feet above sea-level, and dotted over with small islands called hummocks. Between the southern coast (a a) and the line of keys (a' a') the water (e') is very shallow, only navigable to smallest fishing-craft, and dotted over with small low mangrov
. Elements of geology : a text-book for colleges and for the general reader. Geology. REEFS OF FLORIDA. 157 with its reefs and keys, and Fig. 128 is a section along the line N S. The southern coast (a a) is ridge, elevated twelve to fifteen feet above the sea-level, within which is the Everglades (e) an extensive fresh- water swamp only two or three feet above sea-level, and dotted over with small islands called hummocks. Between the southern coast (a a) and the line of keys (a' a') the water (e') is very shallow, only navigable to smallest fishing-craft, and dotted over with small low mangrove Fig. 128.—Section of same along line NS. Letters indicate the same. The dotted lines show sup- posed previous conditions. A considerable portion of this area, in fact, forms mud-flats at low tide. Between the line of keys (a' a') and the living reef (a" a") there is a ship-channel (e") five to six fathoms deep. Outside the reef (a" a") the bottom slopes rapidly into the almost unfathomable abyss of the Gulf Stream (0 8 8). General Process of Formation.—Now, Agassiz * has proved that not only the living reef but the keys, the southern coast, and the peninsula, certainly as far north as the north shore of the Everglades (d d), and probably on the east side as far north as St. Augustine (d'), have been formed by coral agency. The evidence of this important conclusion is that the rock in all these parts is identical with the reef-rock already described, and with what is even now forming under our eyes on the liv- ing reef (a" a"). It is, moreover, almost certain that the peninsula of Florida has been progressively elongated by the formation of successive barrier reefs, one outside of the other, from the north toward the south, and the successive filling up of the intervening ship-channels, probably by coral debris from the reef and sediments from the mainland. History of Changes —The history of changes was as follows : There was
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
