PEBBLE PHOSPHATE DEPOSITS. 
7 1 
FOSSILS OF THE LAND PEBBLE PHOSPHATE DE¬ 
POSITS. 
It is not the writer’s purpose to include in this paper a descrip¬ 
tive or monographic treatment of the fossils of this formation. It 
is necessary, however, in order to fully understand the beds, to 
make mention of the common fossils and to account for the asso¬ 
ciation of land and marine forms, as well as for the inclusion within 
the beds of fossils of different geologic periods. 
The fossils of the land pebble phosphate deposits include: (i) 
Those that were derived from the underlying formations and hence 
represent animals that lived at a time antedating the phosphate¬ 
bearing formation; and (2), those that are contemporaneous with 
the formation, having lived at the time when the phosphate beds 
were being accumulated. It is sometimes assumed that the fossil 
bones found in the phosphate beds are the source of the phosphoric 
acid. This assumption obviously is entirely erroneous. 
FOSSILS DERIVED FROM THE “BED ROCK." 
The fossils from the “bed rock” in this formation include chiefly 
teeth of sharks and rays, worn pieces of ribs, casts of invertebrates, 
and silicified corals. Of these fossils the sharks’ teeth and silicified 
corals are highly resistant; the pieces of ribs also, have sufficient 
endurance to withstand removal from one formation to another 
The casts of the invertebrates although not particularly resistant will 
nevertheless withstand fully as much attrition as the fragments of 
the “bed rock” marl with which they are associated. Since these 
fossils are found in the “bed rock” marl it is scarcely to be doubted 
that some of them now found in the phosphate beds were derived 
from that formation. 
FOSSILS FROM MIOCENE STREAM AND RIVER DEPOSITS. 
The geologic history of southern Florida leads to the belief that 
the upper Oligocene marl, the “bed rock,” was exposed as a land 
surface during a part or all of the Miocene period. If this is true, 
it is evident that residual material, stream and river deposits were 
accumulated during that time in which doubtless the remains of 
Miocene land animals were preserved. If so, it is apparent that 
when the area was again submerged, the more resistant of the 
Miocene fossils may have been included along with other residual 
