Mesozoic and Cenozoic Geology and Paleontology. 223 
towns of Waushara county, however, are underlaid by a considerable 
thickness of red clay belonging to this formation. The surface eleva- 
tion of the country here is 160 to 200 feet above Lake Michigan, and 
the clays 80 to 100 feet and over in depth, as shown by numerous arte- 
sian well borings that yield a flow of water which is obtained from 
seams of gravel at different horizons in the clay. The clay of eastern 
Waushara county is part of a large clay area that extends up the 
Green Bay valley from Lake Michigan, and it is quite significant, that 
Prof. Irving’s map of this lake deposit shows that it extends within 
about twenty miles of the northeastern part of the driftless area of 
Wisconsin. 
Afterward* he said the lacustrine clays underlie all of the lower 
levels bordering Lake Superior, above which they rise to altitudes of 
between 500 and 600 feet. This carries them well up the front slope 
of the Copper range, and high, also, on the flanks of the Bayfield high- 
land. On the Wisconsin Central, these clays reach to an altitude of 
560 feet, and are finally left, on ascending the railroad line from Lake 
Superior, near where Bad river is first struck, 
The clay varies largely in amount of sandy admixture. There is 
commonly some sand included, though, at times, it seems almost wholly 
absent, and at others to make up the bulk of the formation. The clayey 
matter is always of a red color, and always contains a considerable 
proportion of lime carbonate. The stratification is not always evident, 
but on the shore bluffs of the Apostle islands, it may be seen in the 
darker color of the moist sandy layers as compared with the lighter 
sun-dried clay. In many places, numerous small bowlders, chiefly of 
some dark greenstone-like rock, are to be seen embedded in the clay, 
and pebbles of the same, and other crystalline rocks are abundant. 
On the shores of some of the Apostle islands, and in places along the 
mainland coast, dark-colored bowlders of large size, presumably washed 
out from the clay, are very abundant. The entire thickness of these 
clays can not be less than from 400 to 600 feet, about 100 feet being 
the greatest thickness seen in any one section. 
Mr. E. T. Sweet found a section of the lacustrine sands and clays, 
with gravel and bowlders, on the north bank of the St. Louis river, 
about one-quarter of a mile from Greeley station, 202 feet in thickness. 
In the vicinity of Fon du Lac, and southeast of Superior City, along the 
old St. Paul military road, he found lake terraces at 15, 35, 80 and 120 
feet above the present level of the lake, and an indistinct one at the 
* Geo. of Wisconsin, vol. iii. 
