CHAP. XXXIV.] XOHT1IEUX DRIFT. 265 



were nevertheless anterior in date to the loam of 

 Natchez and Vicksburg. 



There exist in Canada, in the Niagara district, in 

 New York, and other States north of the Ohio, lacus 

 trine and swamp deposits of marl and bog-earth, includ 

 ing the bones of extinct quadrupeds, such as the mas 

 todon, elephant, castoroides, and others, associated 

 with land and freshwater shells of recent species, 

 which are decidedly post-glacial, and often found in 

 hollows in the drift. These may be of contempo 

 raneous date with the loam of Port Hudson and 

 Natchez. 



The northern drift, however, is by no means all of 

 the same age, and as the period of glaciers and ice 

 bergs freighted with erratics is still going on, and has 

 now a wide range in the temperate parts of the 

 Atlantic, bordering the eastern shores of North 

 America, so must we naturally suppose that certain 

 parts of the drift, especially those found at lower 

 levels, and near the sea, may not be more ancient than 

 the loam of the western bluffs of the Mississippi. 



VOL. II. N 



