p.7

7

probable that four fifths of Wisconsin
has been dry land.

The temperature of the climate is
supposed to have been much higher than
a percent during the time from
the deposition of the lower Silurian
to the beginning of the glacial period at the close of the tertiary age. This
long period of high temperature must have
had its excessive warm rains, such as are now
found in some tropical districts, causing
denudations, and transportation of detritus
far beyond any now observed in Wisconsin.

[pencil drawn drawing]

Rivers have cut
their channels through
the overl[a]ying sand rock in numerous places
near the southern margin of the aroic as
represented in this figure.