3Iesozoic and Cmnozoic Oeology and Palceontology. 327 



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 cla^'s 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 fi'om 

 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 claj^s 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 alwa3^s 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, chiefl}' 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 quai'ter 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. 



