PHENOMENA OF DRIFT. 205 



hard quartz rocks, weighing many tons, that have 

 been perfectly rounded and smoothed in this way, 

 and can thence conjecture how fearful must have been 

 the rush and the war of elements, that produced such 

 effects. 



Geologists consider that there have been several 

 periods of drift, on the northern part of this continent; 

 all of them being in a westerly direction, coming from 

 the east. Some ascribe it to the action of ice, either 

 in the form of glaciers, or icebergs; others to the up- 

 heaval of the bottom in some portion of the north sea, 

 sending an indescribable torrent of mingled mud, ice, 

 and water, sweeping over the face of the country; 

 tearing away hills, scooping out valleys, crumbling 

 away various strata of rock, and depositing their ma- 

 terials in different and often far distant localities. 



The fact that the rocks on the sides of some of our 

 highest hills are ground smooth, and marked with 

 scratches and even deep grooves, in the direction 

 which these currents, or masses of ice, took, shows 

 how irresistible must have been their force, and how 

 great their volume. 



In some cases, the action of this drift has been, to 

 cover up good soils, or rocks that are capable of pro- 

 ducing such soils, with immense accumulations of 

 sand and gravel. In other places it has deposited a 

 better class of substances than the original. On the 

 whole, it may be considered that it has done good, by 

 mixing the ruins of various formations; varying the 

 soil, and the consequent productions, over districts 

 that would otherwise have been uniform, and where 

 the want of these various materials might have been 

 severely felt, in all the ordinary occupations of life 

 What must have seemed at the time, wild chaotic 

 confusion and ruin, was then after all a wise pro- 

 vision of God, to prepare this continent more per* 

 fectly for our habitation. 



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