264 Wisconsin Academy of Sciences^ Arts^ and Letters. 



as though the ice, in its withdrawal, had half disclosed a mound 

 lying beneath it. This, though a mere mound, was about equal 

 in height to the adjacent heaps that had been left bj the glacier. 



5. At other points, near the center of the valley, the ice may 

 be seen resting directly upon well assorted, stratified sand and 

 gravel. Level sheets of fine detrital matter extend without dis- 

 turbance of continuity or surface beneath the edge of the glacier. 

 The assortment and stratification of this material was apparently 

 accomplished by sub-glacial streams, which seem afterwards to 

 have found other avenues, when the ice occupied their place, 

 either by settling down from above,. or advancing from behind. 

 The singular fact is that the stratified sands should not have been 

 disturbed. It is very likely true that these fragile formations 

 near the edge of the glacier are heated by conduction from the 

 warm earth surrounding, and by transmission through the com- 

 paratively thin ice, above, and that they are thus enabled to protect 

 themselves from the forcible action of the ice, by melting it as 

 fast as, in its slow motion, it is pressed upon them. 



6. If we now turn to the sides of the valley, we shall see that 

 up to a certain height they are mainly bare of vegetation and pre- 

 sent a fresher and less weathered surface than the slopes above, 

 as though the glacier had recently stood at that hight. If we 

 glance down the valley, we shall see that the upper margin of 

 this surface descends curvingly, much like the contour of the 

 present foot of the glacier. If we descend the valley to the 

 point where this reaches the plain, we shall find the ground mo- 

 raine rising into a low, irregular ridge, which stretches in a broken 

 curve across the valley. The material of this ridge is essentially 

 the same as that of the ground moraine, save that there is notice- 

 ably more sand and gravel in proportion to the coarse material, 

 and the whole is more thoroughly rounded. These remarks re- 

 late to the surface material. The superficial contour, however, 

 assumes quite a difiierent and distinctive aspect. Although but a 

 diminutive ridge itself, not perhaps exceeding twenty feet in 

 height, its surface contour, instead of presenting a simple curving 

 outline, exhibits a complex series of still more diminutive ridges, 

 hills and hummocks, of irregular outline and arrangement, accom- 



