ANNUAL REPORT — -EARLY INVESTIGATIONS. 71 
In his preliminary sketch of the phosphates of Florida, 
George H. Eldridge (66) expresses the view that the entire 
area of Florida was re-submerged to receive the mantle 
of superficial sand which forms such a prominent feature 
of its surface. 
In 1895 J. W. Spencer published a paper (193) in 
which he postulates the elevation of the Antillean and 
surrounding region sufficient to connect the two Amer¬ 
icas by way of the West Indies. Two main periods of 
elevation are recognized. The first occurred in the Plio¬ 
cene period. This is followed by a period of depression 
during the late Pliocene or possibly early Pleistocene, 
which corresponds, Spencer believes, to the Lafayette de¬ 
pression described by McGee. The land rose again to a 
great elevation during Pleistocene time, uniting the con¬ 
tinents by way of the Antillean bridge. A subsidence 
followed in the later Pleistocene, which submerged most 
of Florida. This depression corresponds to the depression 
during which the Columbian series was formed on the 
continent. After this subsidence the land rose 150 to 200 
feet above the present level, with subsequently slight 
depression to its present level. Spencer concludes that 
the Antillean bridge stood 1 from one and a half to two 
and a half miles above the present altitudes of the plains 
which now form the islands: 
“It has been found that there have been two epochs of great 
elevation, namely, in the Pliocene and in the Pleistocene 
periods. Between these there was a subsidence of such depth 
as to drown the continental coastal plains and reduce the 
West Indian region to very small islands, with (probably) a 
shallow connection between the Atlantic and Pacific oceans. 
The mid-Pleistocene depression was not quite so great as the 
earlier and there was probably a strait connecting the two 
oceans. Since that time there have been several oscillations 
of minor degree, with the formation of many small coastal 
canyons and the elevation of terraces and coral reefs.” 
To the conclusion of Spencer, Dali (42) enters a vig¬ 
orous objection. He states (pp. 1544, 1545, 1546) : 
“Dr. J. W. Spencer has propounded some very startling 
