92 THE POPULAR SCIENCE MONTHLY. 



ice either as glaciers or icebergs, or both. A slight inquiry into the 

 nature of aqueous erosion must instantly discredit those views which 

 rely upon its efficacy, and relegate them with the rest to unqualified 

 rejection. 



Water, though supplied in torrents so tremendous as to transport 

 the enormous bowlders which are now found scattered so far from their 

 origin, would toss and tumble these masses over the subjacent rock, 

 breaking, fracturing, and denting the latter, but never impressing it 

 with deep, straight furrows for miles, or scoring it with delicate and 

 reticulatiuGj striae. 



Again, the numerous pebbles and stones which are found upon and 

 through the topmost soils, in gravel-beds and sand-heaps, would have 

 been smoothly rounded like beach-worn agates, and not, as they really 

 are, tattooed and etched with fine lines running the length of the stone. 

 In the grooves of the rock, and in the fine lines of the pebbles, we have 

 evidence of a body firmly held upon the engraved surface, and passed 

 along with undeviating directness and irresistible power. Prof. Agas- 

 siz has traced these flutings upon the rocks of Maine for miles, up hill 

 and down dale, across rivers disappearing upon one side, and reappearing 

 upon the other ; and it is beyond possibility to have a plunging torrent 

 of water, charged with stones and rocks, pursue such continuous and 

 definite traces over the hardest rock. More than that, the action of 

 water has been recorded alongside of these very grooves, both in this 

 country and the Alps, as if to invite attention to the opposite character 

 of the two inscriptions. The original traces are firm, direct rulings, and 

 the water-marks beneath them, as in rocky troughs, are waving lines 

 and cracks of denudation following the relative softness of the rock. 



Untenable as this theory is, after such considerations, it seems more 

 inadequate when we remember that this element was to transport for 

 leagues masses weighing hundreds and thousands of tons, and to raise 

 them to almost inaccessible altitudes, to arrange them in long succession 

 across intervening slopes. We find, on the contrary, that moderate- 

 sized bowlders have sunk to the bottoms of streams, which have re- 

 moved the soil and lighter material upon which they rested, allowing 

 them, otherwise undisturbed, to sink almost vertically to their beds. 

 Lastly, the high mounds and " horsebacks " associated with this era, 

 composed of unassorted gravel, pebbles, bowlders, and clay, would have 

 been arranged in superimposed layers. Their present composition is 

 almost irrefragable evidence that water had no part in their construc- 

 tion. 



On the other hand, the demonstration of the adequacy of the glacial 

 theory to account for these phenomena is found only in a study of those 

 glacial effects which are contemporaneous, or have been witnessed 

 within the memory of man. By establishing an exact accordance be- 

 tween these latter, wherever examined, and the indications of erosion 

 and transportation wide-spread over the continents, we prove the iden- 



