1891.] Geology and Paleontology. 735 
GEOLOGY AND PALEONTOLOGY. 
Elevation of America in the Cenozoic Periods.—Mr. W. 
H. Dall writes as follows to the Geological Magazine-for May, 1891: 
“ I notice in recent numbers of the Geological Magazine that Mr. 
Upham has been discussing his views on the elevation of the Gulf of 
Mexico, etc. It seems a pity that gentlemen who desire to launch 
such startling hypotheses should not devote more time to settling the 
facts upon which these hypotheses are based before promulgating their 
new views. As the statements made by Mr. Upham may be taken as 
properly verified, and more confusion be thereby occasioned, permit 
me to call attention to a few facts which have been verified. 
‘1. The late Dr. Maack, when on the Isthmus of Darien, did not 
collect any Pleistocene fossils from the summit of the Atrato divide, 
763 feet above the sea, 2. The Pleistocene fossils collected by Dr. 
Maack were from an elevation of only 150 feet on the Panama side, 
ten miles from Panama City. The fossils above this height collected 
by Dr. Maack are Eocene or Miocene exclusively, and related to the 
Miocene fauna of Santa Domingo, as indeed was pointed out by Gabb 
nearly twenty years ago (Proc. Am. Philo, Soc., Vol. XII., p. 572). 
3- The summit or dividing line is not fossiliferous, and is probably not 
later than the Mesozoic epoch. 
“I may add, from information to be shortly published, that the 
Supposed great elevation of Florida at any time since the later Eocene 
is as improbable as any hypothesis which could well be conceived. 
The conclusions which the facts necessitate in the case of Florida may 
be briefly outlined as follows: During the later Eocene, West-Central 
Florida was an island, like one of the Bahamas at present, composed 
exclusively of organic marine sediments, which in the Vicksburg epoch 
attained an unbroken thickness of more than 1,000 feet. The whole 
submarine plateau above which the present Florida rises may turn out 
to be of this age and constitution. This island had a land-shell fauna 
derived from the south, The strait between the island and the main 
coast north of it was more than fifty miles wide at the narrowest point, 
and was only closed at the beginning of the Pliocene. There have 
been gentle changes of level since the Eocene, but nothing violent, 
and the vertical range has been small, The Eocene and the old 
Miocene faunas were of a subtropical character, like the Antillean 
fauna at present. A change took place in mid-Miocene by which a 
cool, temperate, or colder water fauna invaded the Floridan region 
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