CHAPTER XV. 



GLACIAL LAKE SAGINAW. 



By Frank B. Taylor. 



HISTORY OF THE LAKE. 



OUTLINE OF HISTORY. 



Glacial Lake Saginaw occupied the. Saginaw basin, and in its first period was an independ- 

 ent contemporary of the later stages of Lake Mauniee. After being a western extension of 

 Lake Arkona it had another period of independent existence during the time of Lake Whittle- 

 sey. Later, it was again merged with the greater waters east of the "thumb," first with Lake 

 Wayne, which discharged eastward past Syracuse, N. Y., and later with Lake Warren, which 

 discharged westward. Still later, it formed part of Lake Lundy, which again discharged east- 

 ward past Syracuse. 



While Lake Saginaw was independent and while it was merged with Lakes Arkona and 

 Warren, its outlet was westward through the Grand River channel. At other times its outlet 

 was eastward past Sjnracuse. 



EARLY LAKE SAGINAW. 



The earliest beginnings of Lake Saginaw were just after the building of the Flint moraine 

 and the making of the early western part of the Imlay channel (from Flint to Maple Rapids). 

 The lake was scarcely more than a pond in its earliest stages, and began to be large enough to 

 make a beach by wave action only after the ice had retreated from the Henderson moraine. 



Between Elsie and Duplain and eastward from Elsie to Flushing a very faint fragmentary 

 shore line — in places a faint lake cliff, but more commonly a narrow, low ridge of gravel — lies 

 10 to 15 feet 1 above the much stronger Arkona ridges and 720 to 725 feet (aneroid) above sea 

 level. This is called the Duplain beach, or the first beach of Lake Saginaw. It is very imma- 

 ture, for it follows all the sinuosities of the ground like a contour line. When it was abandoned 

 the lake had accomplished extremely little toward straightening its shore. Only two or three 

 fragments of this beach were observed north of Grand River, and its limits are not yet known. 



With continued recession of the ice front, the lake expanded in size until it merged with 

 Lake Arkona. For a time it was a rather long, narrow, crescent-shaped lake reaching north- 

 ward between the ice and the land about as far as it did eastward. Before it widened out and 

 approached its greatest extent as an independent lake it seems probable that its outlet had been 

 cut down so that its shore line was as low as the level of the highest Arkona beach. Although 

 such a beach has not been observed as an independent form, it seems certain that it must have 

 existed and that it was the second beach of Lake Saginaw. 



LAKES SAGINAW AND ARKONA. 



When the ice barrier withdrew from the "thumb," a strait was opened across its northern 

 low part and the waters on both sides merged at one level, making Lake Arkona and adding to 

 it the area of Lake Saginaw. In this change Lake Saginaw, with its undisturbed outlet, became 

 the controlling factor. The new lake became merely a greatly enlarged Lake Saginaw, the con- 

 ditions of the latter lake and its outlet remaining unchanged. At this time the Arkona beaches 

 began to be formed and the first one probably merged with the preexisting second beach of 

 Lake Saginaw to form one continuous shore. The only change was that greater waves now 



1 This beach was called the Duplain beach in an earlier publication, entitled Correlation of Erie-Huron beaches with outlets and moraines 

 in southeastern Michigan: Bull. Geo]. Soc. America, vol. 8, 1896, pp. 53-54. 

 358 



