676 



SCIENCE. 



[N. S. Vol. II. No. 47. 



Archaean rocks which rise on either side 

 to a heigh th of two or three hundred feet. 

 Evidently there is no space here for a pre- 

 glacial channel of any size, though in build- 

 ing the lower lock upon the canal, which 

 here descends about twentj' feet, it is said 

 that piles were driven to a depth of one 

 hundred feet to secure foundations. Below 

 these locks Half-way Brook joins Wood 

 Creek and a broad, nearly level channel 

 extends northward to Whitehall. It ap- 

 pears evident that the pregiacial drainage 

 went both ways from this Archfean ridge 

 at Fort Ann. 



But, while the present drainage runs east 

 of Fort Ann Mountain to Whitehall, the 

 main line of the depression occupied by 

 Lake Champlain is to be traced west of 

 this mountain thi'ough South Bay, at the 

 head of which there is a pronounced ter- 

 m.inal moraine extending across the depres- 

 sion, which is here about a mile in width, 

 and filling it to a heighth of from two hun- 

 dred to three hundred feet with glacial de- 

 bris. The summit of this moraine is reach- 

 ed on the north side in a distance of about 

 one-half mile, while southward a deposit 

 of kames and of aprons of gravel descend 

 gradually to Half-way Brook, in the vicinity 

 of Fort Ann, a distance of about eight 

 miles. How deeply buried this valley may 

 be it is impossible to tell from surface indica- 

 tions ; though on the north side it is clearly 

 filled in the whole depth to the level of 

 Lake Champlain. It is by no means im- 

 possible that by removing this glacial de- 

 bris there maj'^ be discovered here a feasible 

 route for a ship canal with water running 

 directly from Lake Champlain to the Hud- 

 son. 



Lake G-eorge presents interesting glacial 

 problems throughout its entire length. Mr. 

 Prentiss Baldwin, whose paper on ' The 

 Pleistocene History of the Lake Champlain 

 Valley ' (American Geologist, Vol. XIII., 

 March, 1794) sheds a flood of light upon 



that region, left his notes upon Lake George 

 unpublished. Failing to accompany me as 

 he intended he gave me the benefit of his 

 knowledge of the region, which had led 

 him to surmise that the lake was held in 

 place by morainic dams at each end, and 

 that the pregiacial drainage of the depres- 

 sion ran both ways, the divide being at the 

 hundred islands between Tongue Mountain 

 and Shelving Bock. Of this theorj' I was 

 able to find abundant evidence. 



The lake is 326 feet above tide and 225 

 above Lake Champlain, running for half its 

 distance parallel with the Champlain and 

 distant from it not more than four or five 

 miles, there being between them a mountain 

 range reaching at one point a summit of 

 nearlj' 3,000 feet. The descent of the water 

 at Ticonderoga is effected by two falls less 

 than a mile apart ; but, extending from the 

 steamboat landing at Baldwin, there is 

 ample space for a buried channel west of 

 the falls ; while just west of the upper fall 

 a small stream exposes a section which 

 shows compact glacial tiU filling the space 

 down certainly to the level of the top of 

 the lower fall. Northward from this point 

 a well-defined depression about half a mile 

 wide extends directly onward across Trout 

 Brook, around Mount Hope, reaching Lake 

 Champlain half-way between Ticonderoga 

 and' Crown Point. This depression is occu- 

 pied by level- topped deposits of Champlain 

 clay through which small streams have cut 

 deep depressions without exposing rock. 

 There can be little doubt that the former 

 drainage of the north end of the Lake 

 George depression extended by this route 

 to Lake Champlain. 



At the south end of Lake George the phe- 

 nomena are equally or even still more inter- 

 esting. The di-aiuage of this part of the 

 lake was not by Caldwell, but through Dun- 

 ham's Bay to the east of French Mountain. 

 For assistance in discovering the facts I am 

 much indebted to Mr. Edward Eggleston, 



