210 GEOLOGY OF EASTERN WISCONSIN. 



In the same region, howlders of clay, which probably originated 

 in the argillaceous layers of the Cincinnati, group, occur, imbedded 

 in the common drift mass. 



Immediately beyond this, in the northern part of Eagle, and on- 

 ward, where the range passes over the thick, heavy beds of the ISTiag- 

 ara Group, the drift is characterized by great blocks of that . forma- 

 tion, often but little eroded. Here, as well as southward, there is 

 present a very considerable portion of well-worn, white, compact, 

 fine-grained, often cherty, dolomite, that probably came from the 

 Waukesha beds of the Niagara Grroup, on the east side of the Kange. 

 When we reach the central and northern parts of Washington 

 county, large quantities of dolomitic sand enter into the composition 

 of the drift. This is especially true of the eastern -flank. The sand 

 arises unquestionably from the crushing of the granular dolomites of 

 the Racine limestone, which is the prevailing rock, to the east and 

 M^hich underlies the Range in part in this region. The northern and 

 southern limits of this sand are very nearly coincident with the 

 northern and southern limits of the granular rock in the vicinity of 

 the Range. 



Large bowlders of brecciated limestone, containing Pentamerus 6h- 

 longus, are found in this region, and on the west side of the Range in 

 the towns of Kewaskum, Ashford and Auburn, beds crowded with 

 this fossil are found in situ. 



In the northern part of Sheboygan and the southern part of Mani- 

 towoc counties, blocks from the Upper Coral and Racine beds, along 

 which the ridge runs, form the most marked constituent of the drift, 

 and similar facts are true to the extremity of the Range. 



It appears then that throughout its extent, the neighboring or un- 

 derlying rock has contributed a noticeable element to the composition 

 of the Range. To this extent its local origin is clearly demonstrated. 

 At the same time it is an equally conspicuous fact that there is pres- 

 ent at all points a large percentage of material which had a more re- 

 mote origin. It is not difficult at a single point t.o find specimens 

 representing several of the formations of this state besides those of 

 Michigan. Native Copper is found quite frequeatly at all points 

 along the Range, and must have traveled from one to three hundred 

 miles. It is evident then that the agency which produced the Range, 

 gathered its material all along its course for at least three hundred 

 miles to the northward, and tha,t its largest accumulations were in 

 the immediate vicinity of the deposit. 



Structure. — The formation presents both the stratified and un- 

 stratified condition. If we could trust to such exposures as wj s; e 



