SECOND ANNUAL REPORT—SOUTHERN EEORIDA. 
213 
twenty feet. These figures, making due allowance for the scantiness 
of the data and the unreliability of well records unless accompanied by 
samples, shows that the maximum thickness may be fifty feet along the 
coastal outcrops and perhaps more inland. 
Physiographic Expression:—L. Agassiz and subsequent observers 
noted that the oolite ledges near Miami and Cocoanut Grove have a 
steep seaward face, and slope off in a succession of low ridges toward 
the Everglades. Shaler also noted along the bluff back of the present 
shore, evidences of erosion by waves indicating an uplift of the coast. 
The ridges back from the bluff appear to have a general trend to the 
west of north. The absence of soil, and quality of the rock surface, 
indicate that these ridges are to be accounted for by original manner 
of deposition, or by erosion during uplift, and not by erosion since; 
yet, that there has been some removal of rock is proved by the potholes, 
large springs, and such water work as the Punch Bowl and the shallow 
gorge of Arch Creek. 
The slight variations in elevation of much of the rock back of Bis- 
cayne Bay is indicated by the accompanying view of a large quarry 
for railroad ballast, at Key. (PI. ix, fig 1.) 
The maximum elevation of the ledges south of Miami may be thirty 
feet above sea level. The maximum elevation on Long Key in the 
Everglades is about eight feet, and at New River about eight feet. 
Paleontologic Characteristics:—The Miami oolite varies in content 
of well-preserved fossils, but is a distinctly fossiliferous rock. The 
animal remains comprise molluscan shells, echinoids and corals. The 
corals are not reef builders and one at least is plentiful in the Bay of 
Florida today. Collections by T. Wayland Vaughan near Miami in 
the winter of 1907-1908, yielded two species of corals and fourteen of 
mollusks, all sixteen species being Recent. Of twenty-six species col¬ 
lected along the drainage ditch west of Fort Lauderdale, by George C. 
Matson in the same winter, Dr. Vaughan specifically determined twenty 
as Recent, and one as Pliocene. Many small heads of coral (Sider- 
astrea) were thrown up by the dredge. 
Areal Distribution:—The most northern exposure of oolite known 
to the writer is west of Delray. The rock outcrops on Long Key and 
the neighboring keys in the Everglades, fifteen miles west of the south¬ 
western corner of the Biscayne Pineland and was found by Griswold 
twenty miles west of Miami. How far west it extends under the Ever¬ 
glades, farther north than Fort Lauderdale, is not established. 
Structure :—At the type locality, Miami, the rock is plainly strati¬ 
fied and crossbedded, as is shown by the accompanying photograph of 
a face, in a quarry. The bedding is that of water-borne sediments. No 
regional tilt can be distinguished from the outcrops though the proba¬ 
bilities are that the formation has a slight dip to the west. 
