. Elements of geology : a text-book for colleges and for the general reader. Geology. 554 CENOZOIC ERA-AGE OF MAMMALS. curves about the Great Lakes and through Iowa, and thence northwest- ward on the north side of the Missouri, through Dakota, into British America. The discovery of this moraine, which we owe chiefly to Ohamberlin and Upham, must be regarded as a complete demonstra- tion of the existence of the ice-sheet. In the map (Fig. 931) the. Ice-sheet Boundary. B Second Ice- sheet Moraine. [7/|Direction of Striae. E Boundary of Lake Agassiz. B Appalachian Range. Fig. 931.—Map showing the
. Elements of geology : a text-book for colleges and for the general reader. Geology. 554 CENOZOIC ERA-AGE OF MAMMALS. curves about the Great Lakes and through Iowa, and thence northwest- ward on the north side of the Missouri, through Dakota, into British America. The discovery of this moraine, which we owe chiefly to Ohamberlin and Upham, must be regarded as a complete demonstra- tion of the existence of the ice-sheet. In the map (Fig. 931) the. Ice-sheet Boundary. B Second Ice- sheet Moraine. [7/|Direction of Striae. E Boundary of Lake Agassiz. B Appalachian Range. Fig. 931.—Map showing the Extreme Boundary of the Ice-sheet, the Second Ice-sheet Moraine, and the Outlines of Lake Agassiz. strong line shows the extreme limit of the first advance, the dotted lines the moraine formed by the second advance of the ice-sheet. In its last retreat many subordinate moraines were left one behind another. We have represented mainly the most advanced. Thus we have clear evidence of a second glacial and an interglacial epoch. That this interglacial epoch was of considerable length is shown by the existence of a forest-bed between the two glacial tills (Newberry). Again, since melting and retreat of the ice-sheet must. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
