M UNITED STATES. 



being toftier, because they had yet lost no part of 

 %vhat the lapse of ages and the repeated fall of 

 "waters has taken from them, rendered the action of 

 these waters much more forcible by their height 

 and steepness ; their colder summits were covered 

 for a longer time with mcae copious snows, and 

 larger fields of ice ; and when the heat of summer, 

 of less duration certainly, yet not less intense^ 

 melted this ice and snow, the torrents thus produced 

 tore up the declivities best furnished with earth, 

 hollowed out deeper gullies, and carried along witk 

 them ample spoils, which accumulated on the lowest 

 steps of the mountains. Every succeeding year 

 fresh fragments came to choke up the tracks of for- 

 mer years ; and the torrents, stopped by mounds of 

 their own raising, acquired fresh strength as they in* 

 creased in volume, and, attacking them in several 

 points, forced their way through them in the most 

 feeble. The waters then opened for themselves 

 new and varying tracks through the softest mud, for 

 the heaviest substances would always remain behind 

 for want of slope and impulsive force ; and by these 

 processes, repeated for ages, the ancient beds of 

 torrents became valleys ; the former shores and 

 alluvions became coasts and plains ; and the rivers, 

 descending from level, to level, leaving their heaviest 

 burdens on slope after slope, depositing in succession 

 the lighter and more soluble, incessantly encroached 

 on the domains ot the ocean by accumulations of 

 sand, mud, pebbles, and trees, which served to con* 

 jiect the other materials together- 

 Even in the present day the Mississippi exhibits to 



