i8S2. TO Trans. N. V. Ac. Set. 



over, the valleys are cup-shaped, even the large river valley exhibiting 

 this feature at a number of points cited by the writer. 



Nothing but glacial action is competent to explain the peculiar shape 

 and positions of these hills and valleys ; and the glacier which deposited 

 them must have moved in a general north and south direction, bearing, 

 however, eastwardly to the east of Cayuga Lake, and westwardly 

 west of Seneca Lake. The long axes of all the smaller lakes in this 

 region prolonged, converge toward a point on the present Canadian 

 shore of Ontario. This fact would seem to indicate conclusively that 

 the glacier radiated in cutting through, or passing over, the mountain 

 ridge, exerting, as has been said above, its maximum of force 

 about Cayuga and Seneca lakes. The amount of erosion indicates 

 that the glacier occupied this region for an immensely long period ; and 

 the writer thinks he is supported by the evidence in believing it one of 

 the hrst to come and last to go of all the ice-streams which swept over 

 New York State. The evidence is, morccver, conclusive that the di- 

 rection of the glacial current in this locality was not south-westerly, as 

 generally maintained by geologists. It may have been a mere deflec- 

 tion of the great south-westerly current, but if so the deflection was 

 permanent. Its great depth — about 2,000 feet from the bottom of 

 Seneca Lake to the top of the highlands on either side, to say nothing 

 of the mass upon iheir summits — must have greatly influenced its retro- 

 grade movement ; and it is therefore possible that it may have blocked 

 the entrance to the St. Lawrence and thus have held back the waters 

 which formed some of the ancient lake regions. The last of 

 these ridges is 200 feet above the present level of the lake, and termi- 

 nates in the vicinity of Great Sodus Bay. East of this point, the val- 

 leys were too deep to admit of a continuous beach being formed ; hence 

 all the higher hills were islands, and the waters circulated freely 

 through the valleys, depositing brick-clays in many of them. [A line of 

 elevations was given illustrating these points.] There are, however, 

 no fossils in these clays, showing that the water was very cold and not 

 far distant from ice — doubtless the foot of the retreating glacier. 



The writer quoted from Hitchcock {Pop. Science Monthly, Dec. 

 1 88 1,) and Newberry (Geological Survey of Ohio, Vol. II.) in reference 

 (0 the motion of the ice, etc., in the lake region ; and from Geikie 

 (" The Great Ice Age"), in explanation of the causes operating to pro- 

 duce the peculiar arrangement of the hills. The latter author describes 

 such hills as occurring in broad valleys in Scotland, and believes that 

 they are formed underneath the glaciers by alternations of lateral pres- 

 sure. In the region under consideration there was a broad shallow 

 valley, as shown by the depression in the Medina sandstone, and there 

 must have been great and striking alternations of pressure, at least 



