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Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume IV (1876-1877)

Chamberlin, T. C.
On the extent and significance of the Wisconsin Kettle moraine,   pp. [unnumbered]-234 PDF (11.1 MB)


Page 233


Wisconsin Kettle Mioraine2
to be accumulated during the accumulation of the moraine, and
through the agency of glacial floods; while it is even more cer-
tain, that other vegetal deposits accumulated much subsequently,
as those found in the red clays of Wisconsin, which are lacustrine
deposits of the great lakes formed after the recession of the glacier.
It would be too much to assume that all plant remains, found
south of the moraine, antedate its formation, but it is safe to
affirm that, with only phenomenal exceptions, e. g., such as escaped
glacial abrasion, all north of it are more recent.
   The bearing of these definite determinations of the glacial outlines
 and movements upon the question of the origin of the remarkable
 driftless area of Wisconsin, Minnesota, Iowa and Illinois (see map)
 was early perceived, and it was clearly foreseen that this line of
 investigation promised a demonstrative solution of the problem.
 The driftles3 area manifestly owes its origin to the divergence of
 the glaciers through the Lake Superior channel, on the one hand,
 and that of Green Bay and Lake Michigan, on the other, and to
 the obstacle presented by the highlands of northern Wisconsin
 and Michigan. This obstacle the glacier surmounted, and passed
 some distance down the southern slope, but apparently not in
 sufficient thickness to overcome the melting and wasting to which
 it was subjected, and so it terminated midway the slope. But
 the deep, massive ice currents of the great channels pushed far
 on to the south, converging toward each other; and, if they did
 not actually unite, at least commingled their debris south of the
 driftless area.' An instance closely similar to this, considered
 from a dynamical point of view, may be seen, at the present
 termination of the Viesch glacier, and illustrations of the general
 principles involved in the explanation may be seen in connection
 with several other Alpine glaciers.
 If the evidence -adduced to show that the Kettle moraine was
 due to an advance of the glaciers be trustworthy, then, to the
 extent of that advance, whether much or little, the moraine marks
 a secondary period of glaciation, with an interval of deglaciation
 X Compare N. H. Winchell In An. Rep., Geol. of Minn., 1876, and R. D. Irving,
Geol. of
 Wis., Vol. II, 1877, whose views are closely analogous to the above and
each to the other but
are not strictly identical. See, also, J. D. Dana, Am. Jour. Sci., April,
1878.
233


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