CHAPTER III. 
RED CLAY AND DRIFT OF GREEN BAY AND WISCONSIN. 
One of the most striking geological features of the region of the great North 
American lakes is the universal presence of loose diluvial matter, deposited since 
the convulsions that have taken place in the metamorphic and igneous rocks. 
Although the general elevation of the superficial materials is not very different, 
each lake seems to have a system of its own, differing in colour and stratification 
from the rest. On Lake Champlain and the valley of the St. Lawrence, to a 
height of five hundred feet above the ocean, marine shells are found in the drift. 
On Lake Erie, the beds of marly clay and sand which surround its western half, 
elevated from five hundred to six hundred and fifty feet above tide-water, are 
almost destitute of shells; and those rare ones yet found are fresh-water and land 
shells. These are a Planorbis and a Helicina, found by myself in the “blue marly 
clay” stratum at Cleveland, fifteen feet above the lake-level, the same I had seen 
in the Loess of New Harmony and St. Louis. 
The Lake Erie System extends across Canada and Michigan, by way of Lake St. 
Clair and the River St. Clair, to Lake Huron, and embraces a portion of its southern 
extremity. 
Rising from Lake Michigan there is another deposit, covering a large tract in 
Wisconsin, of a very different external cast. This is the “red clay” deposit, which 
is seen at Milwaukie on the south, and traced by me without interruption to the 
Falls of Wolf River. At Sheboygan, it extends more inland than at Milwaukie, 
and is seen to the foot of the high gravel ridges dividing the waters of Sheboygan 
River from those of Rock River and Lake Winnebago. After crossing this ridge, 
it reappears in the valley of Lake Winnebago, at an elevation of one hundred and 
fifty to two hundred and fifty feet above its surface, equal to four hundred and ten 
feet above Lake Michigan, or nine hundred and eighty-five above the ocean. The 
valleys of Lake Winnebago, and the Fox (or Neenah) and Wolf Rivers, and the 
peninsula between Lake Michigan and Green Bay, are composed of this clay; and 
it is so uniform in its composition and colour, that specimens taken from Lake 
Shawano, and Lake Winnebago, from Green Bay or Milwaukie, could not be identified 
if the labels were misplaced. It is so argillaceous, that bricks are everywhere made 
