220 SKETCHES OF CREATION. 



the present channel is a narrow and shallow one, excava- 

 ted through the surface of the loose materials which fill 

 the more extensive ancient channel. In Ohio and Indiana 

 these buried river-beds are of frequent occurrence. The 

 ancient gorge of the Niagara River was filled by the ob- 

 literating agency of this continental glacier. For ages 

 and ages the river had patiently labored upon this exca- 

 vation, as it has since done upon the existing one ; but the 

 glacier came with its cubic miles of rubbish, and wiped out 

 the trifling furrow, leaving the surface comparatively level, 

 and making it necessary for the river to begin anew its 

 work when the invading glacier had disappeared. The 

 excavation of lake basins is sometimes attributed to this 

 agency, but these may have been partly the result of sub- 

 sequent aqueous action. It was probably the force which 

 dug the shores of northern seas into their numerous deep 

 and narrow fiords, as. can be seen upon the coast of Maine, 

 and the European and Asiatic shores of the Arctic Ocean. 

 It bore southward, over distances of twenty, fifty, and even 

 five hundred miles, fragments of Northern rocks, some of 

 which are of enormous magnitude. One in Bradford, Mas- 

 sachusetts, is thirty feet each way, and weighs not less than 

 four and a half millions of pounds. A boulder of jaspery 

 conglomerate, weighing about seven tons, was transported 

 three quarters of a mile by the class of 1862, and mounted 

 upon the campus of the University of Michigan, an impei v 

 ishable monument to their memory and their enterprise. 

 The native home of this huge mass is the northern shore 

 of Lake Huron, where the formation is found in place, and 

 where I have seen detached and rounded masses weighing 

 probably a hundred tons. These fragments have thus been 

 transported over lakes, sounds, and seas. Masses of native 

 copper from Lake Superior are strewn over Wisconsin and 

 Lower Michigan, and have wandered even into Ohio and 



