File:Map showing the glaciated area of North America – Geology (1907) (14589819089).jpg

Identifier: geology00cham (find matches)
Title: Geology
Year: 1907 (1900s)
Authors: Chamberlin, Thomas C. (Thomas Chrowder), 1843-1928 Salisbury, Rollin D., 1859- joint author
Subjects: Geology
Publisher: New York, H. Holt and co.
Contributing Library: Internet Archive
Digitizing Sponsor: Internet Archive

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Text Appearing Before Image:
ese centers are indicated in Fig. 470, where the linesof movement, the extension in different directions, and the configura-tion of the borders at certain stages are indicated. From this mapit will be seen that the radiation was unsymmetrical in all cases, beinggreatest southward, southwestward, and westward. From the Labradorean center, the extension was notably greatestto the southwest, in which direction the limit is only found some 1600miles from the center of dispersion. This limit lies in about 37° 30latitude, and is the most southerly point of the great lowland glaciationof the period. The extension of the Keewatin ice-sheet to the south-ward was scarcely less great, finding its limit in Kansas and Missouri,about 1500 miles from its center, while to the west and southwestit extended 800 to 1000 miles toward the foot-hills of the Rocky Moun-tains. The details of ice movement northward from these two centers arenot well known, but the fact of general northward movement is estab-
Text Appearing After Image:
Fig. 470.—Map showing the glaciated area of North America. The heavy line acrossthe United States represents the limit of glaciation. The lobate outline of theice of some of the later stages is also shown. The arrows back from the edgesof the drift-sheets indicate direction of ice movement, as recorded by striae. Theclotted lines represent direction ol movement generalized from the recorded striae.They radiate from the three centers indicated in the text. The short arrowsin the western part of the United States indicate the general distribution anddirection of movement of the ice in that part of the continent. There were doubt-less glaciers in some areas where they are not represented. 331 832 QEOWG\ lished. The Keewatin sheet pushed northwestward to the mouth of the Mackenziej and probably to Hanks Land, northward and northeast-ward to the Arctic Islands,1 and eastward to Hudson Bay, and into confluence with the Labradorean sheet. The latter pushed northwardinto Ungava Hay, eastwar

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