ANCIENT GLACH5HS. 



103 



souri Valley and spread eastward to the Mississippi River, 

 south of the unglaciated driftless area, and there became 

 confluent with a similar movement which had been di- 

 rected by the valleys of Lake Michigan and Lake Erie. 

 There can be little doubt that President Chamberlin's ex- 

 planation is in the main correct, and we have in this an- 

 other illustration of the analogy between the behaviour of 

 moving ice and that of moving water. 



.b'iG. 34.— Section of the east-and-west glacial furrows, on Kelly's Island, pre- 

 served by Mr. Younglove. Fine sediment rests immediately on the rock, 

 with washed pebbles'at the surface. 



The accompanying illustrations will give a better idea 

 than words can do of the celebrated glacial grooves on the 

 hard limestone islands near Sandusky, in the western part 



