MUSEUM OF COMPARATIVE ZOOLOGY. 143 
istic reef material, and is composed to a certain extent of corals, which 
have evidently grown in place, this reef gives proof of a recent elevation 
of the shore to the height of about twenty-five feet. There has been 
a considerable loss by corrosive action, how great cannot be determined, 
in the height of this reef. It is throughout honeycombed by subter- 
ranean water passages, and the surface of the rock is much disrupted by 
the overturning of trees in times of hurricanes, when the roots entangled 
in the crevices of the rock break blocks away from their bedding. 
The Miami Reef, as I propose to term this interesting accumulation of 
coral, extends northwardly with occasional interruptions for a great dis- 
tance along the eastern shore of Florida. North of Dumbfoundling Bay 
it appears gradually to lose its character as a true coral reef, and to take 
on the general nature of coquina. It appears to be the same elevation 
that is traceable as far north as the northern part of Indian River, near 
Titusville’ I have only observed this ridge at certain points. North 
of Lake Worth I have not observed any corals in the material. It ap- 
pears that from Jupiter’s Inlet to Titusville it is mainly composed of 
molluscan remains. It is therefore not certain that it is all of the same 
age as the Miami Reef, but the fringe of beach material follows con- 
tinuously on the line of that reef, first in an almost meridional direction, 
then turning at Lake Worth to the northwest. There can be no doubt 
that the eastern shore of Florida from Miami to Titusville, and probably 
all to the northward, has its position determined by the strong resist- 
ance which this consolidated beach deposit has offered to the action 
of the sea. 
The steep escarpment which this barrier of old beach material pre- 
sents, which is now elevated to a score of feet or more above its original 
position, indicates that it long withstood the beating of the ocean waves. 
The barrier of drifting sands now lying along the coast between this 
escarpment and the open ocean has apparently been constructed in very 
modern times, since the last elevation of the shore. A part of the cut- 
ting which formed the escarpments of this reef evidently took place 
during the process of elevation which brought the reef to its present 
altitude. This is indicated by the fact that sea caves and other re- 
entrants are formed in the cliffs at a considerable height above the 
‘present plane of the sea. 
The effect of this reef on the drainage of Florida is very great. 
Although the rivers at many points have found their way across the 
elevation, either by subterranean streams or through the low points of 
the barrier, it serves to retain the land waters, and to bring into the 
