Mesozoic and Ocenozoic Geology ojid Paloeontology. 325 



rocks, which lie beneath them all. At one place, in sinking a well, 

 after passing through the surface deposits, blue clay was penetrated 

 70 feet in thickness, followed by 18 feet of sand, gravel, and clay, be- 

 low which a light-colored limestone was reached. There is ample prooi 

 that the Winnipeg basin has been filled with water to the foot of the 

 second prairie steppe, in recent geological times. In digging wells in 

 the cit}' of Winnipeg, wood bark and leaves are sometimes met with, 

 and fresh-water shells occur in the sand deposits between the south 

 end of Lake Manitoba and the Assineboine river, about 50 feet above 

 the former. The level of Lake Winnipeg above the sea is 710 feet, 

 St. Martin's lake 737 feet. Lake Manitoba 752 feet, Lake Winnipegosis 

 and Cedar lake 770 feet, and Lake of the Woods 1,042 feet. 



The drift strife* in the eastern part of Wisconsin are exceedingly 

 variable. Between the Kettle range and Lake Michigan, their course 

 is from S. 4° W. to S. 116° W, Between the Kettle range and the 

 Green Bay and Rock River vallej^, their course is from S. 12° W. to 

 S. 59° E. In the trough of the Green Bay and Rock River valle}^, 

 their course is from S. 41° W. to S. 7° E. And on the west slope ot 

 the Green Bay and Rock River valley, from S. 94° W. to S. 24° W. 

 The diagram used to illustrate the course of these striae, resembles the 

 flowing vanes of an ostrich feather, with the shaft pointing to the 

 northeast. 



The drift deposits are separated in ascending order, into: 1st — Bowl- 

 der clay; 2d — Beach formation; 3d — Lower red clay; 4th — A beach 

 formation; 5th — Upper red clay; 6th — Beach formations. The eleva- 

 tion of the beach ridge which marks the western limit of these de- 

 posits above Lake Michigan, near the Illinois line, is 55 feet; farther 

 north, from 40 to 80 feet. North of Milwaukee there is a well-defined 

 terrace, nearly parallel to the lake shore, from 50 to 100 feet high. In 

 the vicinity of Sturgeon Bay, the terrace is replaced by a beach ridge 

 of rather fine yellow sand. Along Green Bay, between Egg Harbor 

 and the mouth of Sturgeon Bay, terraces of rock sustain a relation to 

 the present shore similar to the terraces farther south. These rise, in 

 some cases, almost verticall}^ to a height of more than 100 feet. The 

 distance between them and the ba}^ varies from a few rods to half a 

 mile or more, and the interval is strewn with water-worn fragments of 

 rock and occasional slight beach ridges. 



In Central Wisconsin, the courses of the striae are not less variable, 

 thougli but few have been observed. In Dane county, they vary from 



* Geo. of Wisconsin, vol. ii, 1877. 



