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AMERICAN NATURALIST. 
Vol. IV. JANUARY, 1871. — No. 11. 
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THE ANCIENT LAKES OF WESTERN AMERICA: 
THEIR DEPOSITS AND DRAINAGE.* 
BY PROF. J. S. NEWBERRY, LL. D. 
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THe wonderful collections of fossil plants and animal 
remains brought by Dr. Hayden from the country bordering 
the Upper Missouri have been shown by his observations, 
and the researches of Mr. Meek, to have been derived from 
deposits made in extensive fresh-water lakes ; lakes, which 
once oceupied much of the region lying immediately east of 
the Rocky Mountains, but which have now totally disap- 
peared. The sediments that accumulated in the bottoms of 
these old lakes show that in the earliest periods of their his- 
tory they contained salt water, at least that the sea had ac- 
cess to them, and their waters were more or less impregnated 
with salt, so as to be inhabited by oysters and other marine 
or estuary mollusks. In due time the continental elevation 
which brought all the country west of the Mississippi up out 
of the widespread Cretaceous sea, raised these lake-basins 
altogether above the sea level and surrounded them with a 
broad expanse of dry land. Then ensued one of the most 
interesting chapters in the geological history of our conti- 
nent, and one that, if fairly written out, could not fail to be 
read with pleasure by all intelligent persons. The details of 
*From Dr. Hayden's forthcoming “ Sun Pictures of the Rocky Mountains.” 
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AMER. NATURALIST, VOL. IV. 81 (641) 
