POST-TERTIARY PERIOD. 



557 



below, because the stream is unable to wear clown its bed, and is 

 more or less dammed up by the barrier. 



The following figures represent terraces on rivers in New Eng- 

 land, as figured by Hitchcock, and illustrate both the regularities 

 and irregularities of level among them. Fig. 833 is from the vi- 

 cinity of Haclley, Mass., on the Connecticut ; fig. 834 from Hins- 



Figs. 833-835. 



^\9Z. 



\b«/ 



53 



\_38^ 



\MW 



33 



28 





54: / 











-^22 ^27_/ 



Sections of terraced valleys in Xew England, with the heights of the terraces in feet: 833, 

 on the Connecticut, at Hadley; B, a brook; M, Mill River; H, Hatfield; C, Connecticut 

 River; H, Hadley; 834, on the Ashuelot, at Hinsdale; 835, on the Connecticut, at Wal- 

 pole. 



dale, N.H., on the Ashuelot Eiver ; fig. 835 from Walpole, N.H., on 

 the Connecticut. In the last the opposite terraces of 83 and 94 feet 

 are probably parts of one and the same level ; and so also the up- 

 permost, 226 and 243. The subordinate terraces are quite nume- 

 rous on the left side, arising in part from the fact that two streams, 

 Cold and Saxon Eivers, enter the Connecticut near by. 



Other considerations bearing on this subject, and essential to 

 right conclusions, are presented in the chapter beyond, on rivers. 



General Observations. 



Among the results on the American continent of the elevations 

 of the Terrace epoch were the following: (1) the expansion and 

 elevation of the land bringing it nearly or quite to its present out- 



