IS THE WHITE RIVER TERTIARY AN 
ZEOLIAN FORMATION? 
W. D. MATTHEW. 
WHEN the Cenozoic of the Great Plains of western North 
America was explored in the fifties and sixties, the theory was. 
formulated that it was deposited as sediment in a succession 
of vast fresh-water lakes. This view was generally held until 
the recent explorations, especially under auspices of the United 
States Geological Survey, which have caused it to be consider- 
ably modified. The Loup Fork has been shown to be largely 
a flood-plain deposit, the Pleistocene chiefly zolian; and Mr. 
Darton has lately traced an extensive system of river deposits 
overlying the White River clays. The main body of the White 
River formation, consisting of fine-grained calcareous “ clay,” 
or chalk, with intercalated beds and lenses of sandstone, usually 
of limited extent and in subordinate amount, has, I believe, 
been universally considered lacustrine. 
There are some very serious difficulties, stratigraphic and 
paleontologic, in the way of this theory, and observations in 
Kansas, Nebraska, and Colorado, during the last two summers, 
suggested to the writer another view, which appears to do 
away with these difficulties. 
OBJECTIONS TO THE LACUSTRINE HYPOTHESIS. 
I. Stratigraphic.—(a) We must assume the former existence 
of a vast lake covering a large part of Nebraska, Colorado, 
Wyoming, South Dakota, and perhaps extending even farther 
northward, with an area dwarfing into insignificance any exist- 
ing lake. We must assume an eastern and southern barrier 
high enough and extensive enough to hold in these waters 
during the entire Oligocene period, which yet entirely escaped 
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