288 The American Geologist. 
November, 1901) 
earlier glacial papers. Several very noteworthy papers by 
others, also, as Elias Lewis, Jr.,t and Prof. J. S. Newberry ,t 
relating to Long Island and the Hudson valley, are similarly 
overlooked in his bibliography. 
From consideration of the amount and probable rate 
of the rise of the Champlain and St. Lawrence region from 
the Late Glacial and Postgla'cial marine submergence, 
Woodworth estimates the duration of the Postglacial epoch 
as somewhere between 20,000 and 100,000 years. The pres- 
ent writer has shown, however, that nearly all the uplifting 
of the Lake Agassiz area took place probably within so 
short a time as about one thousand years, during the ex- 
istence of that lake, since which time the region has been 
affected only by very slight changes of level. Likewise 
probably the uprise of the St. Lawrence basin was at first 
relatively rapid, so that it might all take place within the 
period of about 7,000 or 6,000 years which is indicated for 
Postglacial time in that part of the northern United States 
and Canada by Prof. N. H. Winchell in his studies of the 
recession of the Falls of St. Anthony, with which my studies 
of the Niagara falls and gorge well coincide. The former 
estimate of the period since the Ice age as tens of thousands 
of years, still advocated by Gilbert and Woodworth, is op- 
posed by a great range of well accordant evidences on the 
glaciated areas of both North America and Europe. 
This Hudson-Champlain area, made classic in glacial 
geology by the work of C. H. Hitchcock, Baldwin, Baron de 
Geer, Gilbert, Merrill, Peet, Woodworth, and others, which 
through the writings of Hitchcock and Dana gave the name 
Champlain to the closing epoch of the Ice age, deserves yet 
further work of detailed surveys, with exact levelling for 
determination of the relations of all its lacustrine and marine 
shore lines. No other area of our continent promises more 
important information concerning the Glacial and Recent 
periods. 
It should also be added that the deeply submerged outer 
fjord of the Hudson, made known with exact soundings and 
charting by Lindenkohl, is the key to the causes of the 
t Pop. Sci. Monthly, vol. x, pp. 434-446, Feb., 1877. 
t Pop. Sci. Monthly, vol. xill, pp. 641-660, Oct., 1878. 
