120 J.W.SPENCER — EECONSTKUCTION OP ANTILLEAN CONTINENT. 



Through the physical study, the writer infers that the Antillean- con- 

 tinent lately existed somewhat as shown by the drainage, but in the vari- 

 ous oscillations of level Central America was warped upwards and cut 

 off the western drainage, which appears to have extended into the Pacific 

 ocean, as shown by the basins opposite to the gulf of Mexico and Carib- 

 bean sea on the southern side of the isthmuses of Tehuantepec and 

 Panama. While the barrier of Central America was being raised, as 

 illustrated by measured examples already cited on page 108, the Antil- 

 lean basins sank. On the surface of the land a good example of similar 

 movement may be seen in the Jordan-Akabah valley, which has sunk 

 bodily for thousands of feet to 2,000 feet below^ sealevel, yet without 

 obliterating the topography of the Jordan valley, even where obstructed 

 by the transverse barrier between it and the gulf of Akabah. As to the 

 dates of the deformation of the Antillean continent we shall inquire 

 later. 



Accepting the foregoing inferences as to the meaning of the submerged 

 valleys and plains, it would appear that the magnitude of the conti- 

 nental elevation varied; that after making allowances for foldings and 

 amplified marginal depressions the northern side of the Mexican gulf 

 has suffered a depression of not less than 8,000 feet and perhaps some- 

 what more; that Yucatan has gone down 12,000 feet; that the Greater 

 Antilles have been depressed 10,000 or 12,000 feet and the southeastern 

 margin of the continent nearly the same amount. AVhile the Caribbean 

 basin has in part become depressed to about 15,000 feet, yet it is hardly 

 likely that any part of the surrounding lands except mountain ridges 

 ever stood at that elevation above their present surfaces. The two Amer- 

 icas were united and the Atlantic currents were deflected eastward. 

 While the Antillean lands of that day were greatly elevated, the plains of 

 the now depressed basins were at no great elevations above the Atlantic, 

 between which and the Pacific some elevated insular masses were appar- 

 ently being slowly pushed up. While the Antillean elevation lasted long 

 enough for canyons to be cut back to the depths given, yet the time 

 was too short to allow of the dissection of the interior of Florida and the 

 border islands by deep canyons. The climate of the elevated continent 

 with the attendant meteoric conditions must have been quite different 

 from those prevailing today. 



Mid-Tertiary Subsidence of the Region of the West Indies. 



The earlier terrestrial condition of the Antilles will be passed over 

 after stating that in the Cretaceous period, or before extensive accumu- 

 lations of mechanical deposits were formed, the sediments were mostly 



