File:The ice age in North America and its bearing upon the antiquity of man. 5th ed. with many new maps and illus., enl. and rewritten to incorporate the facts that bring it up to date, with chapters on (14595814518).jpg

Identifier: iceageinnorthame00wriguoft (find matches)
Title: The ice age in North America and its bearing upon the antiquity of man. 5th ed. with many new maps and illus., enl. and rewritten to incorporate the facts that bring it up to date, with chapters on Lake Agassiz and the Probable cause of glaciation
Year: 1911 (1910s)
Authors: Wright, G. Frederick (George Frederick), 1838-1921 Upham, Warren, 1850-1934
Subjects: Glacial epoch Glaciers
Publisher: Oberlin, Ohio Bibliotheca Sacra Co
Contributing Library: Gerstein - University of Toronto
Digitizing Sponsor: MSN

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ers. In some cases, as Professor Toddhas shown, these valleys terminate abruptly in the water-parting, as if being the continuation of glacial streams fromthe east, which had originated upon the ice-lobe while itfilled the James Yalley. Professor Todd, to whom the exploration of this regionwas assigned, thus describes the Missouri coteau : This moraine consists of loops, convex usually toward thewest and south, but in rare cases toward the northwest, as willbe seen. These loops connect at re-entrant angles pointingtoward the northeast and east, which are usually sharp, andsometimes are extended into elongated ridges. The morainevaries in elevation with the region on which it rests. Its rela-tive height is usually great at the head of the re-entrantangles or interlobular moraines. These frequently stand outlike great promontories, rising from one hundred and fifty tofour hundred feet above the plain around them. At the bot-tom of a loop the moraine is apt to be slight or wanting, if on
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Fi<i 67. TERMINAL MORAINES. 217 lower land ; the flow of water from the ice probably havingcarried away the debris as rapidly as it was pushed forward bythe ice. On the other hand, in case the loop was pushed upan inclined pUme, and the water did not find free escape, it(tlie loop) is well developed all around. The outer moraine insome places is very rough and stony ; at other points it is asmooth, broad ridge, with few knobs, and covered with a deep,fertile soil.* Dr. G. M. Dawson early discovered the sipjnificance ofthis great Missouri coteau in its extension north of theUnited States boundary-line, and thus describes it: On approaching its base, which is always well defined at adistance, a gradual ascent is made, amounting, in a distance oftwenty-five miles, to over 150 feet. The surface at the sametime becomes more markedly undulating, as, on nearing TurtleMountain from the east, till almost before one is aware of thechange, the trail is winding among a confusion of abruptlyron

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