SECOND ANNUAL REPORT-SOUTHERN FLORIDA. 
187 
The rock ridges of the east coast comprise the outcrops of oolitic 
limestone, which extend from north of Miami to Homestead, in Dade 
County, and separate the great saw-grass swamp of the Everglades 
from the fringe of mangrove swamps and salt prairie along the west¬ 
ern shore of Biscayne Bay. This rocky country forms part of the 
Biscayne pineland. The area of these outcrops is a matter of con¬ 
jecture. The relations of rock ridge and prairie along the western 
edge of the pineland are extremely intricate; the elevation of the out¬ 
crops falls gradually to the level of the Everglades and the pineland 
tapers off in a series of rocky keys or islands, of which Long Key is 
the largest, extending fully fifteen miles beyond the southwest corner 
of the main body of the pineland. To the north the outcrops are 
mantled by sand before the elevation of the rock surface has become 
as low as six feet above mean tide. The area is estimated at 200 
square miles. North of New River, between the sea and the Ever¬ 
glades, except for the coquina near the beaches, outcrops of rock are 
few and scattered. In the Everglades some of the keys have a rocky 
foundation, sucli being reported nearly to Lake Okeechobee, but so 
far as known the only ones to form bare rock ridges are Long Key 
and those related to it, none of which reaches as far north as the paral¬ 
lel of Miami. 
On the west coast of southern Florida hard rock outcrops are more 
scattered than on the east, but cover a wider area. Throughout the 
region of pine island and cypress strands, limestone projects here and 
there through the sands and is found along the roads from Fort Myers 
to Fort Shackelford and from Fort Myers past Immokalee to the head 
of Allens River. There are, moreover, areas of bare rock, extending 
as narrow, interrupted strips of varying length up to several miles, 
running through the pinelands. 
A peculiar feature of the rock outcrops of southern Florida is the 
erosion of the surface. On the west coast, where the limestones are 
denser and finer than on the east coast, the rocks weather irregularly 
into rounded knobs and lumps a few inches to a foot above the general 
level of the surrounding sands, making it difficult to drive a wagon 
across bare expanses. In the rocky area of the east coast, the softer 
oolitic limestone weathers into angular shapes, the rock surface is ex¬ 
tremely rough and walking is a task that requires constant watchful¬ 
ness. The ground is strewn with loose, sharply angular fragments, 
products of weathering and the disruptive power of tree roots, and 
fixed angular masses a foot or so high with irregularly pointed sum¬ 
mits and jagged outlines vaguely suggest miniature pagodas. 
With this surficial erosion there has been solution underground. 
Next to the bristling rock surface, the most striking feature of the 
Biscayne pineland south of Miami is the presence of innumerable 
