400 LIFE OF THE PLEISTOCENE 



naiades and other river mollusks, besides other life, will be discovered when this 

 area is systematically studied. 



Life is not to be looked for, however, in any abundance or variety, on the 

 wave-beaten beaches, where few animals can live, and where the shells are soon 

 reduced to fragments by the pounding of the waves; but rather in the sheltered 

 spots, in bays, behind protecting bars and wherever fine sand or silt accumu- 

 lates and affords a preserving medium for the remains of life. The silts de- 

 posited in the outlet east and south of Fort Wayne should have been admirable 

 mediums for such preservation. At Sandusky there are several beaches which 

 developed bars, behind which a safe habitat was afforded. 1 



LAKE WHITTLESEY 



During the Lake Whittlesey stage, Defiance Bay, at the west end of the 

 lake, probably provided a suitable habitat for the biota, after the Fort Wayne 

 outlet was abandoned. The vicinity of Grand Haven, Muskegon, and Grand 

 Rapids, as well as the area covered by glacial Lake Saginaw, including the 

 Grand River outlet, should be carefully studied for evidences of life. 



LAKE WARREN 



The waters of Lake Warren undoubtedly laid down numerous deposits which 

 entombed the life of this stage. Mollusks have already been found at Badaxe 

 and in other localities, and further search will doutless reveal many more. A 

 small bay formed near Caro looks very promising, as does also another, smaller, 

 bay near Flint. As a guide to the beaches and sedimentary strata of these 

 lakes, Leverett's work "Glacial Formations and Drainage Features of the 

 Erie and Ohio Basins" will be of great value, the areas of the old beaches being 

 clearly mapped. 



Evidences of life should also be looked for in the old glacial rivers serving as 

 outlets for Lake Saginaw, especially the Imlay outlet channel connecting Lake 

 Saginaw with Lake Chicago. The outlet near La Peer, because of its width 

 and the apparent shallowness of the water, should contain many shallow-water 

 forms of life. The glacial river bed, between the second and the third moraines, 

 should contain the evidences of a naiad fauna. These outlets are well illus- 

 trated on plate vi, of Taylor's paper in the Geological Survey of Michigan. 2 

 The Ann Arbor Folio 3 covers much of the same region and accurately maps 

 the old beaches and bars. In Monroe County good maps are shown; 4 also 



1 Leverett, Monograph, XLI, plate 22. 



5 Rep. State Board of Geol. Surv., Mich., 1901, pp. 111-117. 



3 U. S. Geol. Surv., Atlas, No. 155. 



< Geol. Surv. Mich., VII, Pt. 1, 1900, plate xiii, p. 140, et seq. 



