ii6 The American Geologist. ^^^^t, i904. 
peninsula the occurrence of deep subterranean channels in 
the Tertiary limestone. 
He says, after stating that the water of the subterranean 
drainage comes from considerable depths : 
"There is no way in which we can account for the excavation 
of the subterranean channels . . . except by the supposition that they 
were made as caverns in the Hmestone rock, with all their parts above 
the erosion base level. We have to suppose considerable subsidence to 
account for these inverted syphons. It is, indeed, not likely that sound- 
ings would give evidence of value as to the original horizontal plain of 
the exit, for under the existing conditions the channels would be filled 
in.'' * 
He further states that the water coming from depths of at 
least 800 feet in wells, has displaced the original salt water, 
indicating a -recent elevation to at least this amount. We know 
of no reason why it should bQ so limited, as the rock favorable 
for the production of such channels reaches to an ascertained 
depth of over 2000 feet. It is also well known that these lime- 
stones favor the formation of subterranean drainage channels 
in place of canyons and valleys, thereby removing the necessity 
of such valleys as Dr. Dall demands. 
Thus Dr. Dall's only real argument against my hypothesis 
(of a late Tertiary or early Pleistocene connection of Florida 
and Cuba) and his own opinion that the oscillations of Flori- 
da have not exceeded 50-100 feet are not supported when the 
facts are looked into, nor are his conclusions sustained not- 
withstandmg the opinions of his associates, as shown above. 
These gentlemen having been referred to, I may be permitted 
to mention the results of independent and actual workers in 
the same line of investigations as my own. 
In America, on the Pacific coast, professor George David- 
son,! and on the Atlantic side Dr. Warren Upham,t almost 
simultaneously with myself interpreted the submarine valleys 
in the continental shelf as submerged land features. ]\Ir. A. 
Lindenkohl* had brought to light the deep canyon of the Hud- 
son river, showing that the region has lately been depressed 
to a much greater depth than that which divides Florida from 
• Id., pp. 154-155. 
+ Bull. Cal Acad. Sci., vol. ii, 1SS7, pp. 265, and Ap. 13. Rep., U. S. Coast 
Surv. for 1887 (1889). 
t Bull. Geol. Soc. Am., vol. i, 1889, pp. 563 567. and in Geo!. Mag. Load 
Dec. 3, 1890, vol. vii, p. 492. 
