Page 7

PHYSIOGRAPHY AND CLIMATE
hills and other eminences, and carrying along a prodigious
amount of rock waste in the form of clay, sand, rock fragments
and bowiders. Muheh of this debris was ground fine and forms
the present soil. The hardest rocks resisted the grinding and
are now found scattered over the surface of the ground as
glacial bowiders, some of which weighl inany tolls.
In Canada the work of the glacier consisted mainly in the
removal of all loose material. There large areas are almost
entirely bare rock whose grooved and polished surfaces
Fig. 4-View of the surface of the Kettle Moraine which extends nearly north
and south in eastern Wisconsin. It consists of hills of glacial drift at-
taining a height of 200 feet and more, and forming a range of hills from
one mile to several miles wide. See Fig. 5.
show plainly the prolonged scouring action of the glacier. In
the region now included in our northern states the ice did some
eroding, but its most important work was that of deposition.
The load of rock waste which the ice carried was spread un-
evenly over the surface of our northern states and now forms
the soil and many of the hills of these states. As time is reck-
oned in geology the glacial period ended only yesterday. Many
evidences suggest that the glacier melted away in southern
Wisconsin not over 50,000 to 60,000 years ago, by no means a
long time. The glacial period, as a whole, lasted hundreds of
thousands of years. It was not a time of continuous cold,
however, but rather an alternation of several cold periods-