Mr Hiifjli Miller on River- Terracinrj. 2C9 



upon its opposite sides, thougli the eye may take them to 

 correspond. They are arranged in basins, with solid rock 

 narrowing the valley at the foot of each of these, and, on the 

 Connecticut, between mouth and source, he distinguishes of 

 these basins no less than twenty-two. He accepts Eobert 

 Chambers's views respecting intersected deltas for those that 

 are of equal height on both banks ; but the greater number 

 are due to the river alone. Its method of action is not 

 made very clear, but he at least recognises that rivers, as a 

 result of their tortuosity, cut in on one side and deposit on 

 the other; and, although totally at variance with his ideal 

 section of a terraced valley, it appears to be the same 

 method as that which the following pages may perhaps 

 illustrate. Hitchcock distinguished the terraces of the 

 Connecticut into four groups : 



The Lateral, or ordinary terrace ; 



The Delta terrace, being the intersected deltas at the 



mouths of tributary streams ; 

 The Gorge terrace, occurring either above or below 



gorges, and stated to be " intermediate between the 



lateral and delta terraces, graduating into both;" 



and 

 The Glacis terrace, a doubtful group, having a slope away 



from the river, as well as the usual bank towards 



it. 



Such was the importance which Hitchcock assigned to the 

 American terraces, that he proposed to divide the Post- 

 pliocene into three periods : a Drift period, attended by a 

 submergence, which he supposed to amount to 5000 feet; 

 a Beach period, marking the country's emergence ; and a 

 Terrace period, following thereupon.* 



In this country Sir A. C. Eamsay,f Dr Arch. Geikie,| and 



* It has since been determined that the submergence was by no means so 

 great, amounting only to 470 feet at Montreal, and diminishing to 10 to 25 

 feet on the southern shores of New England (Dana's "Manual," 1881). 



+ Physical Geology and Geography of Great Britain (Fifth Edition, p. 530). 



X Manual of Geology (Jukes and Geikie), 1869 ; and Text-Book of Geology, 

 1882, p. 383. 



