54 F. B. TAYLOR — CORRELATION OF BEACHES AND MORAINES. 



of the Pewamo channel, was occupied by a lake. From a point three 

 or four miles east and southeast of Cass City a beach was found extend- 

 ing toward the southwest substantially parallel with the Forest and 

 generally within at most a mile or two to the south. This is called the 

 Du Plain beach, and it marks the shore of lake Saginaw. In some places 

 it is a very conspicuous gravel ridge and is followed many miles by 

 " ridge roads." It is of this character for much of the way from Clio 

 northeast through Ferrandsville nearly to Millington, but in many places 

 between Cass City and Clio it is so duney that it is hard to follow. It is 

 well formed again on the east side of Flint river about two miles north 

 of Flushing. Thence west the land is very flat, and the beach was not 

 found for a number of miles. It is well formed again at Du Plain with 

 a spit, and from near Eureka it was followed in fragments into the 

 Pewamo channel to a point two or three miles southwest of Maple 

 Rapids. It is particularly well formed about a mile east of the latter 

 place. Throughout nearly all its course it lies from 20 to 30 feet above 

 the Forest beach, but the vertical interval seems to increase somewhat 

 toward Maple Rapids. 



DURATION AND RELATIONS. 



The duration of lake Saginaw and its relation to the other lakes of that 

 time remains problematical. Whether it existed only during the third, 

 stage (lake Whittlesey), or also during the fourth stage (Arkona beach), 

 or only during the latter, cannot now be said ; nor is its relation to lake 

 Chicago apparent. It is possible that the Du Plain beach is the con- 

 temporary of the Arkona, lake Saginaw having previously stood for a 

 time at a lower level, but, so far as the two beaches are known to the writer, 

 the Du Plain seems to be stronger than the Arkona. If it was a depres- 

 sion of the north end of the thumb that caused the making of the Arkona 

 beach, then lake Saginaw might have had its relative level raised hy the 

 same movement. If such depression did not effect the Chicago outlet the 

 current in the Pewamo channel might also have been so reduced that it 

 would seem more like a strait than a river. Lake Chicago would still be 

 separated from lake Saginaw, however, by a strait 50 miles long and 

 only one to two miles wide. At any rate,, it would appear that the depth 

 of water in the channel must have been decreased, and hence the velocity 

 of the current through it increased when the waters fell from the Du 

 Plain to the Forest level. More observations, however, are needed before 

 reliable conclusions on these points can be reached. 



Deformations. 



The deformations of the beaches described in this paper are not so 

 marked as in some other areas, but they show some notable peculiarities. 



