38 FLORIDA GEOLOGICAL SURVEY-THIRD ANNUAL REPORT.
have as suggested by Matson*, washed into this deposit from some pre-existing formation. This can not apply, however, to the occasional complete skeletons that are found in these deposits. it is probable that the formation accumulated in comparatively shallow water. That the water was not deep is evident from the irregularity of the stratification and from the occasional cross bedding. Also that the place of accumulation was not far removed from land is indicated by the comparatively coarse material and by the presence of numerous bones of land animals.
CHANGE OF CONDITIONS DURING DEPOSITION.
The land pebble phosphate formation, as previously stated, is not of uniform character throughout, indicating that the conditions varied from time to time during the accumulation of the material. The earliest phase of the formation observed consists of clear quartz grains and very small black pebble phos5phate f orming a stratum one to f our feet in thickness. This material occurs only locally and is non-workable, the phosphate pebble being too small to separate f rom the sand. This phase of the formation may be observed in the pit of the Pierce Phosphate Company, six miles south of Mulberry. The formation divides itself into the workable phosphate stratum and the indurated sands forming a part of the overburden previously described. Strati graphically the most pronounced break in the formation is that which occurs within the phosphate stratum itself, particularly in the northern part of the phosphate field, where the pebble -phosphate conglomerate rests upon the underlying clayey phosphate matrix. This conglomerate grades above very gradually into the overlying gray sands. A change in condition in deposition is clearly indicated. This change probably indicates elevation of the land to the north. Following this elevation there was brought in first the coarse phosphatic material accompanied by the flint and corals, and later the sands which make up the upper member of the formation.
STATE AND GOVERNMENT LANDS IN THE PHOSPHATE SECTION.
Both the State and the National Governments still own lands in the phosphate sections of the State. All State lands have been withdrawn from sale by order of the -Internal Improvement Board until properly classified.