68 NEW YORK STATE MUSEUM 



of heavy cobble beaches at and north of Cannon Corners reached 

 735 feet in altitude, which is very near to the figure 750 feet which 

 has been used for the theoretic height at the north line of the 

 State. It seemed apparent that the up and down movement of the 

 Hudson-Champlain valley must have involved the adjacent Con- 

 necticut valley, and therefore an exploration was made of the latter 

 from Long Island sound to Wells River. This invasion of New 

 England is also necessary for the study of the pleistocene of Long 

 Island, since in position and in glacial history the latter area is a 

 part of the former. 



It was found that the phenomena of submergence in sea-level 

 waters, so obtrusive in the Hudson-Champlain valley, were clear 

 and abundant in the Connecticut valley. The high-level " terraces " 

 and sand plains, of which much has been written, attributing them 

 to deposits of the glacially-flooded river, are really delta deposits 

 made in standing waters at sea level. The plains and terraces are 

 partly contributed, as in the Hudson valley, by glacial outwash 

 and partly by land drainage, and later somewhat distributed and 

 shaped by river work at lower levels. 



The origin of the plains in Massachusetts as static water deposits 

 were recognized by Professor Emerson, and so described in his 

 United States Geological Survey publications, Monograph XXIX, 

 and Holyoke folio, no. 50. His water plane was taken as a datum 

 plane, and it was found practically to mark the upper limit of the 

 standing water from Middletown north to the mouth of Passumpsic 

 river, about 280 miles. Northward from this point the valley was 

 above the sea level. 



In the Connecticut valley the uplifted marine plane has a north- 

 ward rise of 2.30 feet a mile, nearly identical with the gradient in 

 the Hudson valley which is 2.23 feet. But for equal latitudes the 

 Connecticut plane lies about 50 feet higher than the Hudson plane, 

 which makes the isobases or lines of equal uplift lie about 20 de- 

 grees north of west by 20 degrees south of east. 



Following are some of the altitudes in the Connecticut valley: 

 Riverhead, L. I., 120 feet; New Haven, Conn., 180; Middletown, 

 220; Hartford, 280; Springfield, Mass., 300; Brattleboro, Vt, 420; 

 Hanover, N. H., 565 ; Wells River, Vt., 620. These are theoretic 

 altitudes of the datum plane, but are very close to the actual levels 

 of the summit terraces. 



It appears that the west end of Long Island was mostly above 

 this sea while the east end was mostly submerged. The heavy 



