CEOTODY. Florida is an outgrowth of the southern coastal plain, and is of recent geological formation. '['he underlying strata are mostly limestones deposited during the Dpper Eocene age. In the southern part of the peninsula the presence of fossil coral reefs indicates that the land has been built up by successive stages in a process similar to that now going on in the Flori da Keys.
1:EsoracEs. Phosphate rock, the most valuable of the State's mineral resources, occurs along a belt extending from Lake Okee chobee to near Tallahassee. Since the discovery of the deposits in 1888 an important mining in dustry has been developed, the output increasing steadily up to 1899, when the total was 706,677 long tons, valued at more than $2,500,000. In 1900 the production declined to 642,321 tons, ow ing to a decrease in the demand. Three grades of material are produced—hard. rock, land pebble, and river pebble; the proportion of lime phos phate ranges from 50 per cent. in river pebble to
over 80 per cent. in hard rock. Of the latter grade practically the entire output is exported to Europe, where it finds a ready market in spite of the competition of French and Algerian phos phates. The hard-rock and land-pebble deposits are work'ed either by sinking pits through the light overburden or by hydraulic mining. River pebble occurs in the basins of the Peace, Caloosa hatchee, and Mafia rivers, but it is found only along the Peace in deposits of sufficient extent to warrant exploitation. Centrifugal pumps mounted on steam dredges are used for raising tile material from the river-bed. Florida also produces most of the domestic supply of fuller's earth from deposits near Quincy. The output in 1900 was 11,813 short tons, valued at $70,565. There are no metallic mines in the State.