982 



HISTOllICAL GEOLOGY. 



1553. 



height northward, to 260 feet at a distance of 200 miles from Long Island 

 Sound. 



Again, at the mouth of Hudson River, according to F. J. H. Merrill, there 

 is evidence of a Champlain subsidence of 70 feet; 35 miles up the river, at 

 Croton Landing, of 100 feet ; 50 miles up, of 180 feet ; 140 miles up, about 

 Albany, of 335 feet. Farther north the divide between the Albany plain 

 and that of the Champlain region, was evidently covered for awhile by fresh 

 water as stated by S. P. Baldwin ; and hence the rise in level along the 

 Hudson may be regarded as continued along Lake Champlain. A reduced 



copy of a map of Lake Champlain of the 

 Champlain period is here inserted from 

 a paper on the terraces of the lake by 

 Baldwin (1894). On the southern part 

 of the lake, at Benson Landing, terraces 

 extend to 370 feet ; at Orwell, 410 feet ; 

 at Charlotte, Vt., near the middle of the 

 lake, 415 and 450 feet, and they contain 

 marine shells ; at St. Albans, near its 

 north end, 500 feet. Marine shells occur 

 in the terraces of the Vermont side to 

 Addison, or through the northern two 

 thirds of the lake, and at Plattsburgh on 

 the west side. 



On the St. Lawrence, near Montreal, 

 30 miles distant in a nearly north direc- 

 tion from Lake Champlain, shell-beds 

 occur at 520 feet; and up the St. Law- 

 rence, according to Dawson, nearly to 

 Lake Ontario, west of Lake Champlain, 

 at 600 feet. The increase in the height 

 of the terraces northward, as well as land- 

 ward, is here apparent. 



But these heights of beaches and ter- 

 races represent but a small part of the 

 actual change of level. For the land in 

 the preceding period stood higher than 

 now. Adding to the above the minimum 



Map of Lake Champlain in the Champlain period estimate of that elevatiou, the actual 



(transversely lined), with the existing lake ^j^^^unt of Subsidence for southem New 



(cross-lined). 



England is 160 to 170 feet ; for the coast 

 of Maine, 1000 feet or more ; at Montreal, 1500 feet at least, and 1200 feet or 

 more for the Lake Champlain region. A similar addition is required also 

 for the deductions from the heights of all terraces and beaches, including 

 those of the region of the Great Lakes. The facts prove that ice barriers 

 were not concerned in making limits for the lakes ; for the ice had retreated 



