Correspondence. 331 
Professor Kemp also gave a paper on the Physiography of Lake 
George. The observations extending over several years have suggested 
the following conclusions. Lake George occupies a submerged valley 
very similar to many others in the Adirondacks, which are not sub- 
merged. The valley has been largely produced by faulting, and the 
fault-scarps still remain in precipitous clififs, whose sharpness has not 
been much affected by the weathering and erosion. Before the Pleis- 
tocene, the valley was probably a low pass with both a north and a 
south discharge. The portion rich in islands near Pearl point, and the 
Hundred Island house, was probably the divide, and the islands rep- 
resent the old hillocks near the top of the divide. At the south the 
water is backed up by sands and morainal matter in the valleys on 
each side of French mountain, viz. at the head of Kattskill bay, and 
at Caldwell. On the north they are held in by Champlain clays and 
sycnitic gneiss at the Ticonderoga outlet, and probably by morainal 
material at the low pass just south of Rogers rock and leading out to 
the very depressed Trout brook valley, just west of Rogers rock and 
Cook mountains. Trout brook is now as fiiuch as a hundred feet 
lower than lake George at points south of the Ticonderoga barrier. 
The northern barrier is rock because the Ticonderoga river passes 
through a narrow and shallow channel in the exposed ledges a mile 
south of its actual first waterfall. There is a broad flat valley buried 
in clays, however, beneath which an old channel may lie submerged. 
At the same time, the marked depth of the Trout brook valley to the 
west makes this the natural outlet and there is reason to believe from 
the general topography that the discharge passed north into the Cham- 
plain valley near the south boundary of Crown Point. It is also not 
to be overlooked that a valley with much drift leads eastward to lake 
Champlain, from the head of Mason's bay. 
A curious feature that is common to both shores of the lake north 
of Sabbath Day point (and perhaps also south of it), is the presence 
of pot holes of great perfection and as high at times as thirty feet 
above the present level of the lake. These are best developed on 
Indian Kettles point, about two miles north of Hague. They are 
doubtless excavated by lateral or subglacial streams wlien tiie ice filled 
the lake valley, because in no other conceivable wa\' could flowing 
water be forced into such unnatural situations. 
There is great need of a good hydrographic survey of the lake, and 
of detailed pilot charts, with soundings. They would be of great serv- 
ice, not alone to navigators, but to science as well. So far as could be 
learned from local fishermen, whose deep trolling for lake trout gives 
them familiarity with the ]:)Ottoni. there appear to be channels whose 
general trend is parallel with tlie long dimension ofthe lake, and which 
have preciiiitous sides, jjre-cisely iil<e tiie valleys and gulches now vis- 
ilile. The lake is relatively shallow as comi)ared with lake Champlain. 
In lake George, the greatest depth is l)elieved to be near "Anthony's 
Nose." and to reach IGO feet. Mlsewhere the deep parts are placed at 
about ipp fpct more or less. All this, however, requires confirmation 
