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 (14782071612).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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rges. From these observations it would seem to follow that astream of ice presenting a cross-section of about 5,000,000square feet (5,000 feet wide by about 1,000 feet deep) isentering the inlet at an average rate of forty feet per day(seventy feet in the center and ten feet near the margin ofmovement), making al)out 200,000,000 of cubic feet per dayduring the month of August. The preceding remarks uponthe many indirect evidences of rapid motion render the cal-culation perfectly credible. What the rate may be at othertimes of the year there are at present no means of knowing. The indications that the glacier is receding, and that itsvolume is diminishing, are indubitable and numerous. Theislands of southern Alaska are ordinarily covered with forestsof cedar, hemlock, and fir. up to the level of 1,500 or 2,000feet above tide. But to this rule the shores and islands ofthe u)iper part of Glacier Bay are a striking exception. Nearthe mouth of the bay, forests continue to occur as in other
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A MONTH WITH THE MUIR GLACIER. 57 parts, only on a diiuiuislied scale; but in the upper half oftlie bay all the shores and islands are perfectly bare of forests,and the rocks retain in the most exposed situations freshgrooves and striae of glacial origin. It would be impossiblefor rocks so exposed in such a climate to retain these for anindefinite length of time. Far up on the mountains, also,there are remnants of glacial debris in situations such thatthe material could not have resisted erosive agencies for anvgreat length of time. The triangular-shaped terminal moraineon the eastern side, just below the ice-front, presents someinteresting features bearing on the same point. This extendsthree miles below the glacier, and in its lower portions isthinly covered with vegetation. This covering becomes lessand less abundant as the glacier is approached, until, over thelast mile, scarcely any plants at all can be found. Apparentlythis is because theie has not been time for vegetation tospr

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