724 ABSTRACTS OF PAPERS 



Discussion 



Dr. F. B. Taylor: It seems to me that one of the most important points 

 brought out by Professor Goldthwait is the attitude of his highest marine 

 beach and the sources suggested for its isobases. This beach appears to be 

 continuous with Gilbert's Oswego beach. It seems to descend from the vicin- 

 ity of Covey Hill both to the northeast and to the southwest, as though cross- 

 ing the axis of an anticline extending northwest and southeast. Present 

 knowledge of this beach in the basin of Lake Champlain, partly from Wood- 

 worth's observations and partly from my own, suggests that this anticline 

 pitches downward to the southeast, and hence that the isobases bend around 

 across it through something near 180 degrees. The deformed planes of the 

 old beaches of the Great Lake and Winnipeg basins seem to suggest that this 

 anticline may extend to a point at least 50 or 100 miles beyond the northwest 

 corner of Manitoba or half way across the continent from the Atlantic to the 

 Arctic Ocean. 



Professor Goldthwait replied as follows : The isobases shown on the map 

 for the deformation of the highest marine beach are based on data from sev- 

 eral sources. Instrumental measurements of altitude of the beach at two 

 localities on the north side of the St. Lawrence River show that east of 

 Quebec the isobases cross the river nearly at a right angle. 



PRE-GLACIAL COURSE OF THE UPPER HUDSON RIVER 

 BY WILLIAM J. MILLER 



Published as pages 177-186 of this volunie. 



Discussion 



Prof. J. F. Kemp : The character of the topography in the Lake George 

 Valley has some bearing on the question. Lake George consists of three 

 parts : a southern portion of relatively mature topography ; a middle, narrow, 

 filled with islands, and having very precipitous mountainous sides, and a north- 

 ern, with more mature topography again. I have long thought that there 

 were two pre-Glacial valleys, one draining south and one north, with a divide 

 between. For several years, partly with the help of friends and partly in 

 person, I have been accumulating soundings in Lake George, and have the 

 southern two-thirds completed. In the deeper parts the bottom ranges about 

 90 to 100 feet. The greatest depth is near the east shore east of Bolton 

 Landing, and is 175 feet. Doubtless the lake valley is largely drift-filled, and 

 we can not state the depth of the bedrock, but when the soundings are com- 

 pleted at the northern end we can draw the profiles and mal^e some estimates. 

 The depth of the bedrock concerns the old drainage relations in an important 

 way. 



Prof. H. L. Fairchild : For considerable time during the waning of the ice- 

 tongue in the Hudson Valley, the ice must have blocked the present channels 

 of the upper Hudson and of the Sacandaga rivers, and have caused a ponding 

 of the waters in those valleys with a broad lake at Northville. The only pos- 

 sible escape for the waters during this episode was southward into the Mohawk 



