PEBBLE PHOSPHATE DEPOSITS. 
79 
Creek beds. From his examination of these beds in 1891 Dr. W. H. 
Dali was led to believe that, on the evidence of stratigraphy and 
invertebrate Palaeontology, the beds were to be referred to a mid- 
Pliocene stage.* The account given by Dali, however, does not 
appeal to the writer as being conclusive on this point. At the 
mouth of Mare Creek, six miles above Arcadia, Dali observed a 
marl, designated by him as the Arcadia marl, from which, however, 
no characteristic fossils were obtained. Lying upon this marl was 
observed a calcareous and phosphatic sand rock, which was identi¬ 
fied from the marine shells that it contained as lower Pliocene. 
With this phosphatized rock is associated a bone bed. Dali states 
( 1 . c., p. 132) “The mammalian bones at this point appear to lie 
on this stratum, and where it is broken up, as is most commonly 
the case, are mingled with its fragments and blackened in the same 
way.” Three miles down stream at Singleton’s Landing an oyster 
bar was observed which proved from its invertebrate fauna to be 
late Pliocene. Moreover, near Zolfo Springs, this marl was ob¬ 
served to overlie the “phosphate stratum.” From these exposures 
Dali was led to believe that the Peace Creek bone bed lay between 
the lower Pliocene phosphatic sand rock and the upper Pliocene shell 
marl. 
It is to be noted, however, that the bone bed is found on top of 
the phosphatic sand rock, and that there is no evidence that the 
bone bed is present beneath the upper Pliocene shell marl. It is 
true that the upper Pliocene is reported to overlie the phosphatic 
stratum at Zolfo Springs. It is not shown, however, that the bone 
bed is present between the upper Pliocene and the phosphatic sand 
rock. 
It is apparent that both Pliocene and Pleistocene deposits lie 
along Peace River, and have been and are being reworked and re¬ 
accumulated by stream action. It necessarily follows, therefore, 
that the fossils of these formations, or such of them as are sufficiently 
resistant to withstand slight erosion, are intimately mixed in the de¬ 
posits along the river. Moreover, since Peace River cuts into the 
Alum Bluff marl it is to be expected that some of the resistant fos¬ 
sils from that formation, particularly sharks’ teeth, have persisted 
in the river pebble deposits. It is hardly necessary to add that only 
*U. S. Geol. Surv. Bull. 84, pp. 130-133, 1892. 
