GLACIAL LAKES TAYLOK. 309 



separation from the watore of the Lake Erie basin. Both of these 

 beaches have only moderate strength. On the outer part of the 

 "thumb" of Michigan they arc both split up into several fainter lines. 

 Thc}^ are generally gravelly on the ''thumb," but arc sandy elsewhere. 

 They have been studied very little east of Michigan, probably in part 

 because they are weak. 



These beaches mark a transition stage of the lake waters— the 

 transition to Lake Algonquin, the largest of the glacial lakes in the 

 Great Lakes region. The outlet for both stages of Lake Lundy was 

 probably near S^a-acuse, N. Y. (fig. 5), but connection with that region 

 has not been established by continuous tracing. 



On the ''thumb" these two beaches show the most remarkable 

 example of northward splitting that has been found. The outer part 

 of the "thumb" was being elevated while these two beaches were 

 being made, and each one splits from a single beach ridge in the south 

 to four or five separate weaker strands covering a vertical interval of 

 25 or 30 feet. In the area of horizontality the Grassmere and Elkton 

 beaches have altitudes of about 640 and 620 feet, respectively. 



Differential elevation has raised the Warren beach at Alden, N. Y., 

 20 miles east of Buffalo, to an altitude of 845 feet, or about 180 feet 

 higher than the same beach in the area of horizontality in Ohio and 

 southeastern Michigan. In the same region, east of Buffalo, the 

 Lundy or Dana beach is about 150 feet below the Warren beach, 

 and descends toward the south or southwest at a rate not yet accu- 

 rately determined. But the altitude of fragments 30 to 40 miles 

 west of Buffalo being 640 to 645 feet, it seems almost certain that this 

 beach becomes horizontal at some point farther west and at a slightly 

 lower level, indicating that it is the eastern correlative of the Elkton 

 beach of Michigan. On the south side of Lake Erie the attitude of 

 the deformed planes of the higher beaches suggest that the Lundy 

 beach probably becomes horizontal near Erie, Pa., and continues so 

 westward. 



At this time the ice barrier stood not far from the })resent south 

 shore of Lake Ontario north of Buffalo, with relatively long and 

 narrow arms of the lake waters extending east and west along its 

 front. With these Lake Lundy was connected by a strait 25 to 30 

 miles wide, extendmg northward over the Niagara region, the depth 

 of the water being 90 to 100 feet at Buffalo and Niagara Falls. 



GLACIAL LAKES IN THE BASIN OF LAKE ONTARIO. 

 LOCAL GLACIAL LAKES. 



When the Lake Ontario ice lobe had retreated far enough to 



uncover the southern parts of the valleys of the Finger Lakes in 



central New York, small lakes gathered in them, at first as separate 



bodies. With continued recession these lakes were lowered and 



85360°— SM 1912 21 



