PRELIMINARY REPORT ON PEAT.

The soil is nearly everywhere sand, where it is not covered by still more recent deposits, such as peat. Clay seems to be absent, and the limestone is often close to the surface, or barely exposed, as in the Gulf hammock region. Long-leaf pine is the prevailing
tree as far south as Brevard and DeSoto Counties, and south of that it is replaced by a related species (Pinus Caribaea).* Sawpalmetto is the prevailing undergrowth nearly everywhere. The
whole region is dotted with prairies of all sizes, from a few acres to several thousand square miles (if the Everglades be regarded as a prairie) in extent.
This region has been too little explored scientifically to warrant any definite statement about the quantity of peat it may contain, but there are certainly many shallow deposits in and around some of the prairies, lakes and estuaries. The northern part of the Everglades, which is the most extensive (through not the deepest) deposit of peat in Florida, if not the largest in the United States, may be regarded as belonging to this region. Descriptions of this and a few other interesting South Florida peat localities will be found in the following pages, and analyses under localities II, 21, 28 and 8o.
MIAMI LIMESTONE REGION.
(PLATES 2.2, I8, FIGS. 27, 28)
From the vicinity of Fort Lauderdale there extends southwestward a belt of honeycombed limestone rocket of Pleistocene age, with a maximum elevation of about 20 feet above sea-level, forming a part of the rim of the Everglades. North of the latitude of Cocoanut Grove this rock is covered with sand, at first only a few inches deep, or merely filling the holes in the rock, but becoming deeper northward. Southward of the point named, the rock is almost bare of anything but vegetation and a small quantity of humus, except in the vicinity of Homestead, where there are small areas in which the interstices of the rock are filled with a sort of reddish clay,
*For notes on the distribution of this tree in Florida see Tenth Census U. S., vol. 6, p. 207, and agricultural map facing p. 187. (It is there called "pitch pine").
tSeveral botanical writers in recent years have called this "coral rock," or "coralline limestone," its honeycombed appearance probably leading themn to imagine that it was an ancient coral reef like the upper Keys (which will be described farther on); but geologists have known for years that it is nothing of the kind. It does contain a few corals among its fossils, like many other limestones, but these corals form only a minute fraction of the whole mass, and they are not reef-building species, anyway. All this was brought out pretty clearly by Mr. Sanford in the second annual report of this Survey.

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