3l8 SURFACE GEOLOGY. 



in immense amount till it makes a conical pile like a heap of grain upon 

 a floor. When additions are made to the grain upon one side, a motion 

 is induced, and more of the kernels will flow down on that side than 

 were added, because of cohesion. If the floor be slightly inclined, the 

 flow of grain would be greatly facilitated. In a similar manner we may 

 believe the flow of ice down certain valleys will carry with it other parts 

 of the ice sheet, even where much of it is dragged over hills. This rise 

 would always be less than the amount of descent from the top of the ice 

 accumulation. With the ice would be carried the blocks of stone im- 

 bedded in it through the pressure of the weight of the overlying mass. 

 Except near the coast, none of the Greenland ice would show boulders 

 upon the surface, because, unlike the Alpine mer de glace, the mountains 

 are entirely covered, and no moraines could be accumulated by the fall- 

 ing down of fragments from the hillsides. The moraines of Greenland 

 are therefore different from the ordinary heaps displayed on the sides, 

 tops, and ends of Swiss glaciers ; they must accumulate mainly beneath 

 the ice-sheet, and not be visible so long as the ice remains unmelted. 

 The finer parts and the favorably situated blocks would, however, be car- 

 ried along with the glacier to some extent, to be distributed eventually 

 as submarine deposits, or to become a species of residual moraine after 

 the melting. 



Further peculiarities of distribution appear in connection with the sub- 

 glacial streams. From the ends of the glaciers issue muddy torrents 

 derived from the melting of the ice. Immense supplies of heat pene- 

 trate the ice from the sun's rays, which must give rise to very much 

 water, seen also in the numerous surface lakes and streams. As all 

 water seeks the lowest levels attainable, these currents will find a place 

 at the bottom of the ice-sheet, and wear away the rocks and ground- 

 moraines already accumulated into the sea. Hence will arise banks of 

 earth or clay more or less continuous from the ice cliff to the point 

 where the current ceases to transport material. In these banks would 

 be found remains of such marine animals as lived in the vicinity. These 

 deposits remind us of the fossiliferous clays along the coast of New Eng- 

 land, sometimes attaining an altitude of 150 feet. Boulders would occur 

 in this clay, brought by bergs, so that it might be styled boulder clay. 

 This deposit is analogous to that called the Champlain clays. 



