18-4 The American Geologist. March, 1894 
time. In fact, it remained there much longer than it hesi- 
tated at any one stage during its rise, for the deposits of that 
time are much the greatest. Besides, as by far the greatest 
clav deposits arc marine, it is but natural to conclude that 
the greatest sand beds are of the same time. 
At the south end of the lake this decided level is probably 
just at Whitehall, 150 feet, or perhaps it did not reach that 
place. At Plattsburgh the marine shells maybe found up to 
346 feet, but the high level there is somewhat over 400 feet. 
On the La Moille it is at 400 feet. 
The marine limit reported from St. Albams is 65N feet,* 
but that terrace was probably formed by the glacial lake. The 
highest marine level there probably does not exceed 500 feet. 
The method pursued by Baron De Geer,f while it answers 
well on slopes toward the sea, is faulty when applied to such 
an enclosed valley, since it fails to discriminate between the 
marine limit and the glacial hike limit. 
I have constantly referred to terraces, rather than beaches, 
for the reason that beaches are difficult to trace in a rugged 
region, while the valley terraces of that time of floods are very 
clear. 
hake < '/hi mpla in. As the continent in late Pleistocene time 
rose to its present hight. the sea was drained off, but the great 
dam formed by the clay plain to the north changed the char- 
acter of the drainage from that of the preglacial Champlain 
river to the present lake. The fresh water lake was at fust 
50 feet or nit. re higher than now, but the Richelieu has low- 
ered its channel to its present level since. The present lake 
lies mostly well above the preglacial channel, but the southern 
end seems to occupy that part of the old channel and is now 
little broader than a river. 
In closing, I would express my thanks to Mr. Upham for 
many helpful suggestions, to Prof. Hitchcock for the loan of 
valuable maps, and to Mr. ( '. II. Richardson for his company 
and assistance in the field. 
*Baron De Geer, Am. Geologist, vol . xi, p. 30, Jan., 1893. 
|A.m. Geologist, vol. xi, p. 23. 
