BEACHES OF LAKE WHITTLESEY. 745 



main moraine, it seems certain that the early activity of the Tyre channel must have 

 been quite short, as compared with the later period of their combined activity. In 

 no other instance known to the writer is the relation of a great ice dam and the outlet 

 of the waters which it retained so close or so clearl}' and unmistakabty shown. Ten 

 miles north of Ubly the surface of the thumb begins a gradual descent of 200 feet to 

 Lake Huron. The circumstances in this case are such that there can be no possible 

 doubt as to the place of the ice front while this outlet was active. It was not over a 

 mile or two from Ubly, and the outlet river from the col to Cass City flowed close 

 along the foot of the ice front. This position of the outlet was a natural consequence 

 of the fact that the ice front was retreating northward down a slope, which happened 

 to be the lowest part of the rim of the lake. For this reason the outlet hugged the 

 receding ice front, and changed its place as fast as lower points of escape were 

 uncovered. 



By following the course of the Saginaw moraine to the southwest, curving back 

 to the north on the west side of the vallev- and the course of the Port Huron moraine 

 to the southeast, curving back to the northeast in Ontario, we find the exact position 

 of the great ice dam in the basins of Saginaw Baj^ and the south arm of Lake Huron. 

 It onlj remains to locate the contemporar}' ice front in the eastern part of the Erie 

 basin to know the exact boundaries of Lake WhittleseJ^ 



THE BBLMORE BEACH FROM THE UBEX OUTLET TO THE IMAUMEE 



RIVER. 



The writer has examined the beach no farther north than the vicinity 

 of Romeo, Mich., bnt from notes furnished by Taylor its course can be 

 outhned from Emmet to this pohit. From Romeo southward the writer 

 has given it sufficient attention to outhne much of its course from his 

 own notes, but has received from W. H. Sherzer, of the Michigan geological 

 survey, notes concerning its course in Washtenaw County. 



DISTRIBUTION. 



From Emmet the course is southward to the vicinity of Lenox, in 

 northeastern Macomb County. It there curves around to a course nortli of 

 west past Armada to a point about 2 miles northeast of Romeo, where it 

 swings southward and leads through Washington to Clinton River just 

 below Rochester. The village of Rochester stands upon a delta which was 

 formed in connection with this beach. The beach continues in a course 

 west of south for about 12 miles from Rochester, passing IJ miles southeast 

 of Birmingham. It there curves abruptly westward, forming an interesting 

 series of hooks in its curving portion and crosses to the west side of East 

 Rouge River about 2 miles southwest of Birmingham. From this point its 

 course is southwestward throug-h Farniingtou to Plymouth, where it crosses 



