32 FLORIDA GEOLOGICAL SURVEY-SEVENTH ANNUAL REPORT. 
GEOLOGY OF SOUTHERN FLORIDA. 
If the origin of the phosphate deposits is to be understood it 
becomes necessary first of all to obtain a clear conception of the 
geology of the country in which they are found. The areal and 
structural geology of southern Florida is now known with a reason¬ 
able degree of completeness and from this may be deduced the geo¬ 
logical history. The formations exposed at the surface in this part 
of the State include the following: The Tampa and Alum Bluff 
formations which are of Oligocene age; the Bone Valley formation, 
which contains the land pebble phosphates and is of Pliocene, or pos¬ 
sibly late Miocene age; and the Peace Creek beds which contain 
the river pebble phosphates, and are of Pleistocene age. The Ocala 
limestone although not seen at the surface in southern Florida, as 
it lies buried to a considerable depth by these later formations, has 
nevertheless an important relation to the phosphate industry since 
it is reached by all the deep wells of the region, and from it chiefly 
is obtained the water supply for hydraulic mining. 
It is a pleasure to acknowledge in this connection the credit that 
is due those whose investigations have contributed to a knowledge 
of the geology of southern Florida. Among these should be men¬ 
tioned in particular Allen (1846), Conrad (1846), Tuomey (1850), 
Smith (1881), Heilprin (1887)., Dali (1890-1903, 1915), Eldridge 
(1893), Shaler (1893), Matson and Clapp (1909) and Vaughan 
(1910). Without the knowledge of the general geology of Florida, 
to which these writers have contributed, an explanation of the origin 
of the pebble phosphate deposits could not Be given at this time. 
A bibliography of the geology of Florida may be found in the 
First Annual Report of the State Survey pp. 54-108. In addition 
the papers relating specially to the phosphates of Florida are listed 
and reviewed in the Fifth Annual Report of the State Survey, pp. 
67-so, 1913. 
