File:Elements of geology - a text-book for colleges and for the general reader (1892) (20636277253).jpg

Title: Elements of geology : a text-book for colleges and for the general reader
Identifier: elementsofgeolog00leco (find matches)
Year: 1892 (1890s)
Authors: LeConte, Joseph, 1823-1901
Subjects: Geology
Publisher: New York : D. Appleton and Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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550 CENOZOIC ERA—AGE OF MAMMALS. ing, scoring, etc., of the rock show that the agent of the shifting has been ice. Extent.—The general extent of these more conspicuous and char- acteristic phenomena, viz., the glaciation, the stony clay, and the great boivlders, is down to about 40° north latitude. The line of southern limit cuts the Atlantic coast about 40°, near New York; it then bends a little southward to 37° 30' in Southern Illinois, and then turns a little northward again as it passes west, and may be traced northwestward nearly to Montana (Fig. 931), and reappears on the Pacific slope in the
Text Appearing After Image:
Fig. 930.—Moraines of Grape Creek, Sangre del Cristo Mountains, Colorado (after Stevenson). southern portion of British Columbia (Dawson). Beyond this the characteristic phenomena mentioned above are not found, but in the valley of the Mississippi, and on each side to a considerable distance, a superficial gravel and pebble deposit, containing northern bowlders— called by Prof. Hilgard " Orange Sand "—extends to the shores of the Gulf. Evidences of local glaciers in the form of moraines are found abundantly in the Colorado Mountains (Fig. 930). Marine Deposits,—Along the Atlantic coasts we find no marine deposits of this time, for the obvious reason that the continent was then more elevated than now; whatever marine deposits were then formed are now covered by the sea.

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