unconformity

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The record of land life is no less interesting. The earliest land inhabitants of the State yet recorded are the land snails, the shells of which are found sparingly in the Ocala limeetone. This was during Lower Oligocene time. The peninsula land area was then, apparently, an island, access to which was for ordinary land vertebrates probably difficult, or even impossible. It is scarcely to be doubted, however, that birds, bats and perhaps many of the small land animals found their way to the islands. An increased elevation occurred following the formation of the Lower Oligocene limestones. Evidence of this upward movement attended by subsequent depression is afforded by an incongruity between the Lower and Upper Oligocene limestones. This movement, if not actually connecting the islands with the mainland, must at least have greatly narrowed the intervening body of water, and may possibly have permitted land vertebrates to reach the peninsula. If so, their remains will doubtless be found imbedded in the Upper Oligocene formations.

By the close of the Chesapeake Miocene the peninsular area was sufficiently elevated to become connected directly with the continent, thus permitting free migration of land vertebrates from the continent. The remains of land animals occur most commonly in clay beds which were doubtless formed along the borders of lakes, streams, and sinks.

The land animals found in these clays include the mastodon, the elephant, the rhinoceros, the saber-toothed tiger, horses, deer, bison, tapirs, giant sloths and glyptodons. The fossil remains of these animals are widely scattered, occurring over practically all parts of the State, those which have been described come mostly from the Alachua Clays in the vicinity of Archer and Ocala; from Peace Creek in Manatee County; and from the Pliocene beds of the Caloosahatchee River. They are probably of Pliocene and Pleistocene age. The South American representatives in this fauna came doubtless by the way of the Isthmus of Panama after the connection of North and South America.

1

A few silicified or lignified tree trunks have been found, and these, together with occasional leaf impressions occurring in the clay strata of the Chattahoochee group give direct evidence of land vegetation in Florida as early as the Upper Oligocene.

FOSSIL HUMAN REMAINS IN FLORIDA.

No State has preserved more definite record of its early human inhabitants than has Florida. The best known human fossils are those which have been obtained from the borders of the Little Sarasota Bay along the Gulf coast of south Florida. The bones found here are changed to limonite. Human remains were reported from this locality by Judge Webb of Osprey, Florida, and sent to the Smithsonian Institution. During 1886 parts of skeletons were obtained by Joseph Wilcox and Angelo Heilprin. Again in 1887, additional remains were collected by Joseph Wilcox. The rock here is a thin stratum of indurated sandstone lying just below the water's edge.

Human remains were also obtained from Rock Island in Lake Monroe. A fossil skeleton was reported from this locality by Pourtalles and Wyman about 1859.* The writer has recently obtained a second skeleton from this locality. The matrix here is a shell rock. There is no evidence that these formations represent other than comparatively recent deposits. The associated fossil shells are of fresh water species representatives of which live along the river at the present time. The skeleton obtained, however, is firmly imbedded in the rock, and while belonging to the recent geological period, is nevertheless historically speaking, very old.

*Wagner Free Ins. Sci. Trans. Vol. II, p. ii, 1889.

PHOSPHATE.

Phosphate mining is Florida's leading mineral industry, the value of this product now exceeding six million dollars annually. Fully twelve million tons with a value of not less than forty-eight million dollars have been taken from the Florida fields from the beginning of active mining in 1888 to the close of 1907.

References to phosphate in Florida began to appear in literature as early at least as 1883. The Proceedings of the National Museum for 1882, published in 1883, contain (p. 47) an analysis of a phosphatic rock found at Hawthorne. The volume on Mineral Resources by the U. S. Geological Survey for the year 1882, published 1883, contains a reference (p. 523) to phosphatic marl occurring in Clay, Alachua, Wakulla, Duval and Gadsden Counties. These references are repeated in Mineral Resources for 1883-84, and in addition, the occurrence of phosphatic rock between Wakulla and the St. Marks River in Wakulla County is recorded. During 1884 and 1885 exploration of the Florida phosphate was made by Dr. Lawrence C. Johnson of the United States Geological Survey. At this time the line of phosphate was traced from Live Oak, in Suwannee County, to Ocala in Marion County. From samples examined and from popular reports phosphate was believed to occur from Thomasville, Georgia, through Hamilton, Suwannee, Alachua, Marion, Sumter, and Polk Counties to Charlotte Harbor in DeSoto County. Most of the phosphates examined by Johnson were of low grade and occur, as he himself recognized, in formations later than the Vicksburg Limestone. The high grade rock phosphate was not discovered by Johnson at this time. Some of the localities mentioned as being examined by Johnson are Preston Sink, 2 miles north of Waldo; Ft. Harley, 3 miles northwest of Waldo; the Devil's Mill Hopper near Gainesville; Simmons' Quarry, 3 miles west