THE FLORIDA PHOSPHATE DEPOSITS.

Incoherent sand.................................... 2 to 4 feet
Indurated gray sand grading below into phosphate matrix12 to I6 feet Workable phosphate stratum ........................... o10 to 12 feet
Yellow clay marl, "bed rock" (exposed).................. 5 feet
The upper 5 or 6 feet of the sand of this section contain some clay and are stained red by iron oxide. At the base the sands pass gradually into the pebble rock conglomerate. Beneath the pebble rock conglomerate the matrix is more clayey while near the base the clays 'of the matrix are olive green in color. The conglomerate as seen in this pit differs from that seen in the pit of the Coronet Phosphate Company in the absence of corals along the contact line.
The relation between the phosphate bearing formation and the underlying marl or limestone is well seen in the pit of the Pierce Phosphate Company, six miles south of Mulberry. The marl exposed in this pit, as previously stated, has a very roughly eroded surface. (P1. 4, Fig. I.) The phosphate matrix fills these irregularities. At this pit there is observed in places below the workable phosphate matrix one to three feet of material consisting of quartz sand intimately mixed with small black phosphatic pebbles. An old stream channel crosses this pit. In the bed of the stream is fine loose, more or less stratified dark colored sand. This stream where examined has cut (lown to the coarse part of the phosphate matrix and at one point almost cut out this coarse part of the matrix, that is it has cut through the sand and the
upper part of the phosphate formation. This stream occupies approximately the bed of an existing stream and probably indicates that conditions were such formerly as to permit the stream to cut its bed deeper than now, the channel subsequently having been aggraded. Near by in the same pit is a sudden dip in the sand overburden. (P1. 3, Fig. 3.) The point of break gives very much the character of a sink hole.
CONDITION OF DEPOSITION.
In attempting to determine the condition under \vhich the land pebble phosphate formation accumulated, the characteristics of the formation itself should be borne clearly in mind. The formation is more or less definitely stratified. The stratification, however, is irregular, and cross bedding and local sand deposits occur. The phosphate bearing part of the formation is highly fossiliferous containing both land and marine vertebrates. Most of these fossil bones are more or less eroded and water worn, indicatvIng that they have been rolled or washed before reaching their final resting place. Occasionally, however, a complete skeleton occurs. NWater worn bones o f both the land an(1 marine vertebrates could

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