BEARING OF THESE STUDIES 95 



northeast-southwest direction. In the Catskill Mountains and 

 northwest of them the trend of the ice edge was northwest- 

 southeast, as shown by T. C. Chamberlin's and Rich's studies 

 of moraines and striae. Hence the whole mountain group was 

 covered by a large lobe the eastern edge of which transgressed 

 the border of Connecticut and Massachusetts. When the ice 

 edge had left the Catskill Mountains, the lobe vanished rap- 

 idly, so that at Cohoes the ice front had an almost east-west 

 direction. 



The ice crossed the Adirondack Mountains in a south- 

 southwest direction, but it was so thin and the movement was 

 so slow that the relative lack of ice south of them caused the 

 lobes on either side to join and cross each other in the Mohawk 

 Valley. 



In western New York the ice motion was largely determined 

 by the Ontario basin and to some extent by the topography of 

 the Finger Lakes district. 



Confirmations Through the Varve Studies 



The geochronological studies confirm the little which was 

 known about the rate of the ice retreat (see pp. 74-84). Where 

 Emerson at Northampton, Mass., had indications of a halt and 

 readvance, there the clays furnish independent evidence of the 

 same thing. In the same zone as the till-covered varve clays on 

 Lake Winnepesaukee, which Upham described, evidences for a 

 halt are also found on the Connecticut at Claremont. Fifteen 

 miles west of the recessional moraines which Goldthwait mapped 

 at Bethlehem, on the northwestern slope of the White Moun- 

 tains, a readvance is recorded in the clays. In zones where no 

 indications of halts have been found the recession proves to have 

 been more or less rapid. 



It is the same thing with the trend of the ice edge. The ice 

 front, fixed by connections between Cohoes, N. Y., and Concord, 

 N. H., runs at right angles to the general direction of the ice 

 flow. Likewise the simultaneous uncovering of the site of Hud- 



