LAKE HUDSON-OHAMPLAIN. 263 



during the Late Glacial or Champlain epoch is supplied, as I believe, by 

 the shallow submarine channel of the Hudson, which has been traced by 

 the soundings of the United States Coast Survey from about 1-2 miles oif 

 Sandy Hook to a distance of about 90 miles southeast from the Hook/ This 

 submerged channel, lying between the present mouth of the Hudson and 

 the very deep submarine fjord of this river, ranges from 10 to 15 fathoms 

 in depth, with an average width of 1^ miles, along its extent of 80 miles, 

 the depth being measured from the top of its banks, which, with the adja- 

 cent sea-bed, are covered by 15 to 40 fathoms of water, increasing south- 

 eastward with the slope of this margin of the continental plateau. 



During the whole or a considerable part of the time of the glacial 

 Lakes Iroquois and St. Lawrence, this area, stretching 100 miles south- 

 eastward from New York, was probably a land surface across which the 

 Hudson flowed witli a slight descent to the sea. But northward from 

 the present mouth of the Hudson the land stood lower than now, and the 

 amount of its depression, beginning near the city of New York and 

 increasing from south to north, as shown by terraces and deltas of the 

 glacial Lake Hudson-Champlain, which were foi-med before this lake 

 became merged with Lake Iroquois, was nearly 180 feet at West Point, 

 275 feet at Catskill, and 340 feet at Albany and Schenectady." Farther to 

 the north, according to measurements by Baron de Greer of the altitudes 

 of the highest shore marks in the part of the St. Lawrence basin which 

 was filled by the glacial Lake St. Lawrence, formed by the union of the 

 two preceding, the depression was nearly 657 feet at St. Albans, Vt; 640 

 feet on the north side of the Adirondacks, southeast of Moira, N. Y.; 

 625 feet on Mount Royal, at Montreal; and 718 feet on the hills a few 

 miles north of the city of Ottawa.^ From these figures, however, both 

 in the Hudson ani St. Lawrence basins, we must subtract the amount of 

 descent of the Hudson River, which in its channel outside the present 



■A. Lindenkohl, Am. Jour. Sci. (3), Vol. XXIX, pp. 475-480, June, 1885, ami Vol. XLI, pp. 489-499, 

 June, 1891. J. D. Dana, Am. Jour. Sci. (3), Vol. XL, pp. 425-437, Dec, 1890, with map reduced from a 

 chart of the U. S. Coast Survey. 



^ J. S. Newberry, Popular Science Monthly, Vol. XIII, pp. 641-660, Oct., 1878. F. J. H. Merrill, 

 Am. Jour. Sci. (3), Vol. XLI, pp. 460-466, June, 1891. W. M. Davis, Proceedings, Boston Society of 

 Natural History, Vol. XXV, pp. 318-335, 1891. Warren Upham, Bulletin, (i. S. A., Vol. I, 1890, p. 566; 

 Vol. II, 1891, p. 265. 



^Proceedings, Boston Society of Natural History, Vol. XXV, 1892, pp. 454-477, with map. 



