324 PLEISTOCENE OF INDIANA AND MICHIGAN. 



to the Wayne beach, the drop being of course due to a recession in the border of the ice, which 

 permitted the reunion of Lake Saginaw with the larger lake to the east and caused a further 

 lowering of these united waters by about 40 feet. 



The Wayne beach is generally faint, and on the " thumb," where it is gravelly, it shows 

 distinct evidence of submergence and modification after it was made. Except on the "thumb," 

 it is generally sandy and without marked characteristics. In the Saginaw Valley it lies barely 

 below the head of the channel which had served as the outlet of Lake Saginaw. It is quite 

 certain that it had no outlet toward the northwest through the Straits of Mackinac, and it prob- 

 ably drained eastward to the Mohawk, passing along the ice margin, where it rested on the hills 

 south of Syracuse, N..Y. 



LAKE WARREN. 



When the ice front readvanced, covering part of the ground previously vacated, it closed 

 the outlet which had recently been opened near Syracuse and raised the lake to the level of the 

 Warren beach. In the Saginaw Valley the Warren beach passes 20 to 25 feet above the col at 

 the head of the Grand Eiver outlet channel, here extremely flat and much covered with dunes. 



In Michigan the Warren beach extends up to the vicinity of Au Sable River north of Sagi- 

 naw Bay but has not been identified farther. In New York it has been traced for some dis- 

 tance east of Genesee River. Its limits in Ontario have not been determined. While the War- 

 ren beach was being made the Wayne beach was being destroyed, and the Warren beach, like 

 the Whittlesey, shows in some places but not so strongly the characters which indicate rapid 

 accumulation. 



In the later stages of the lake waters, from Lake Arkona on, the area covered by the lakes 

 included not only the basin of Lake Erie but parts of those of Lakes Huron and Ontario also. 

 From New York, Fairchild reports evidences of a readvance and raising of lake level later than 

 the one which affected Lake Warren. That movement, however, appears to have been confined 

 to the Lake Ontario basin and had no effect upon the waters of the Huron-Erie basin. 



The beaches of all the foregoing lakes are horizontal in the southern part of the region they 

 cover, but in the northern part they rise slightly toward the north-northeast. The area of hori- 

 zontality lies southwest of a fine passing about 5 miles north of Birmingham, Mich., to Ashtabula, 

 Ohio. This seems to have been a sort of hinge line for the earlier deforming movements. North 

 of it all the beaches rise gradually in a direction about north-northeast, but the earlier ones 

 begin to rise before the later ones, as if the deforming force had migrated slowly northward, 

 following the retreat of the ice front. 



LAKE LUNDY (LAKE DANA, LAKE ELKTON). 



When the waters fell from Lake Warren they halted first at the Grassmere beach and later 

 at the Lundy (Dana, Elkton) beach, before they finally separated from the waters of the Lake 

 Erie basin. The outlet at both stages was probably near Syracuse, N. Y., but connection with 

 that region has not been established by continuous tracing. It was probably during the time 

 of Lake Lundy and perhaps also during that of Lake Wayne that the great cataracts (allied to 

 Niagara) existed in the hills southeast of Syracuse, N. Y. 



The two beaches have only moderate strength. On the "thumb" they show the most 

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

 "thumb" was being elevated while they were being made, and each beach consequently splits 

 from a single strand to four or five separate weaker strands covering a vertical interval of 25 

 to 30 feet. In the area of horizontality the Grassmere has an altitude of 640 feet and the Lundy 

 (Dana, Elkton) of about 620. feet. Both are generally gravelly on the "thumb" but are sandy 

 elsewhere. They have been studied very little east of Michigan, probably in part because they 

 are weak. They mark the transition to Lake Algonquin, the largest of the glacial lakes in the 

 Great Lakes region. 



