OP THE NOrvTHWESTERN STATES. 



compactly together, like a pavement. On the summit, between the waters of 

 Lake Erie, and the Ohio river, in Northeastern Ohio, the elevations and depressions 

 of the upper drift, are less marked but readily distinguishable. 



The materials are coarse as compared with the lower members, but less coarse 

 than upon the waters of Lake Superior. There was evidently less intensity in the 

 glacial movement, as we approach its southern limit. Some of the boulders are as 

 large, but their numbers are less. In the township of Green, Summit County, Ohio, 

 there is an erratic block of granite 12 feet long, 10 feet broad, and 7 feet thick. 



Along the height of land, there are also patches of boulders of northern and 

 igneous rocks, a few rods across, resembling, on a small scale, those of the Meno- 

 minee and St. Louis rivers. Although the transporting and sorting action appears 

 to have been more powerful at high levels, the abrading action of the drift forces 

 is as conspicuous in valleys as upon mountains. The limestone strata of Sandusky, 

 Ohio, at the level of Lake Erie, which pass beneath the lake, are as thoroughly 

 worn and striated as the conglomerate, and the coal grits 600 feet above lake level. 

 It is the same at Sheboygan, in Wisconsin, where the Niagara limestone is covered 

 by red clay, which the waves of Lake Michigan wash away from the rocks, 

 leaving exposed large warped surfaces of glacial etchings and polished grooves, 

 perfectly fresh and clean. 



Fig. 4. 



Fac-Simile op a Slab of Niagara Limerock, polislied and striated by t 



clay. Sheboygan Light House, Wisconsin. 



;ath tlie red 



Between the Menominee and the Peshattego rivers, the country is not elevated^ 

 but all the exposed knobs and floors of Sienite are thoroughly smoothed and 

 wrought into domes and hollows by ice action from the north. 



