Il8 REVIEWS 



doubtful if this difference, with its resulting relief, should be referred 

 wholly to the Wisconsin or last stage of glaciation. 



Evidence of distinct ice invasions is found in the northernmost part 

 of the lower peninsula in the constituents of the drift, which are such 

 as to show a movement east of south from the Lake Superior region 

 into the Huron basin, another and probably later movement from the 

 Georgian Bay region southwestward across Michigan and onward to 

 southeastern Iowa, as well as the still later movement referable to the 

 Wisconsin stage of glaciation. A single hill north of the Saginaw 

 basin was found to carry Potsdam sandstone from the Lake Superior 

 region, jasper conglomerate from the Georgian Bay region, and gyp- 

 sum from the borders of the Saginaw basin. In the western and 

 southern parts of the peninsula, interglacial soils and peat beds are 

 struck in wells, while in the southeastern part strise, as noted by Sher- 

 zer, suggest distinct ice invasions. 



The paper discusses the lobing of the Wisconsin ice sheet, the 

 development of a succession of moraines, and the lines of discharge 

 for glacial waters. Attention is also given to drumlins which occur 

 near Charlevoix, and to the eskers in the region covered by the Sagi- 

 naw lobe. 



The drumlins seem to be subglacial accumulations, since they con- 

 sist of till which is more thoroughly kneaded or worked over than the 

 till of the neighboring moraines. They appear also to have been 

 built up slowly as the ice moved over them, there being traces of lami- 

 nation concentric with the upper surface of the drumlin. The ice then 

 apparently extended to a strong moraine that passes along the south- 

 east border of the drumlin area. 



The eskers of this region are commonly found in shallow valleys, 

 termed "esker troughs," which were cut in the till. This situation, 

 together with the fact that the eskers, like the till, are composed 

 largely of local rocks, strongly favors the view that their material was 

 derived from the till through the agency of subglacial waters. 



On the Evidence of Post-Newark Normal Faulting in the Crystalline 

 Rocks of Southwestern New England. By William H. Hobbs. 

 Structural work within the belt of crystalline schists of south- 

 western New England has until recently been carried out upon the 

 assumption that the rocks have been deformed solely by a process of 

 folding. Both Dana and Pumpelly have emphasized this assumption 



