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Whitbeck, R. H., 1871-1939 (Ray Hughes) / The geography and economic development of southeastern Wisconsin
(1921)

Chapter II. Physical features and climate of southeastern Wisconsin,   pp. 5-23 PDF (4.8 MB)


Page 6


GEOGRAPHY OF SOUTHEASTERN WISCONSIN
The history of the rocks underlying the region of south-
eastern Wisconsin, therefore, includes three principal events,
each of long duration: (1) the deposition in the sea of the
various kinds of sediments (sand, clay, limestone) which were
slowly cemented into beds of solid rock; (2) the uplift of these
above sea level, and (3) the prolonged weathering, erosion, and
removal of the surface rocks, considerably reducing the general
level of the land.  This is the series of events through
which practically all of the land surface of the earth
has passed at one time or another, and, in inany cases, several
times.
In addition to these three processes, southeastern Wisconsin
has passed through a fourth experience, namely, glaciation.
THE GLAcLL PErIOD
The most recent of the great geological events in Nortlh
America was the glaciation of more than half of the continent.
For some cause, yet unknown, the climate of northern North
America became cold-probably as cold as southern Greenland
is at present. The precipitation which now falls mainly as
rain then fell in the form of snow, and even the summers were
so cold that this snow did not all melt, but accumulated in
enormous quantities. The piling up of the snow was particu-
larly great in Canada, including Labrador and the region west
of Hudson Bay, the centers from which the glaciers moved out-
ward. Year after year and century after century the snow
continued to accumulate in re and ii northern Europe, and
also in the higher mountains all over the world. The snow on
both sides of Hudson Bay is believed to have become several
thousand feet deep. Its own weight, and possibly slight melt-
ing in summer, compressed the snow into ice, and under the
tremendous weight of this ice the bottom layers were so pressed
upon that they were forced to flow outward-especially south-
ward where the temperature was milder and where melting
along the margin of the glacier took place during the warmest
months of the year. The movement of the glacial ice was very
slow, possibly only a few yards or a few rods a year, as is now
the case with the great glacier which covers Greenland.
Soil and loose rocks became frozen into the glacier and were
slowly moved along with it. The glacier moved over hills and
low mountains, through valleys and across plains, removing
everything that was movable, scouring and grinding the rods
over which it passed, deepening some valleys, rounding off
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