DILUVIAL AGENCY. 145 



rock from their original beds, pushed them along before them, 

 the friction rounding off their angles, and reducing many of 

 them to sand and pebbles. Sometimes large masses of rock 

 would get wedged in between, or thrown upon the tops of, 

 blocks or projections of ice, and would be floated to great dis- 

 tances and scattered over the country. Boulder rocks which 

 must have been transported in some such way, have been 

 identified with rocks "in place"' to which they must have orig- 

 inally belonged, from a few hundred yards to several hundred 

 miles to the north of where they were found. Sometimes 

 boulders of great magnitude have been carried over steep and 

 high mountains, and are not unfrequently found lodged upon 

 their summits and scattered over their southern declivities ; 

 and the long-continued passage of rocky fragments and detri- 

 tus transported in this way, has worn scratches, and sometimes 

 deep groves in the mountain rock, all of which have the same 

 general direction, which is nearly north and south proving 

 that such was the general direction of the current. By this 

 operation, which was evidently long-continued, rugged mount- 

 ain escarpments were reduced; deep hollows were filled up, 

 and the face of Nature was made to assume fairer proportions. 

 In short, the terrestrial structure being generally completed, 

 this final operation (to illustrate a great thing .by a diminutive 

 comparison) seems to have been the smoothing and sand- 

 papering process to which it was subjected, before being 

 applied to its ultimate and principal use as the habitation of 

 its future tenant, MAN. 



This superficial smootning and rounding of the earth, and 

 its completion as a habitable globe, being the third member of 

 the Secondary Trinity of terrestrial developments, manifestly 

 bears a certain correspondence to the third member of the 

 Primary Trinity, or the granito-aqueous development, which 



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