GLACIAL LAKE CHICAGO. 355 



Muskegon Lake opens into Lake Michigan. It follows the shore pretty closely to White Lake 

 and extends up the border of that lake about to Whitehall. It is present on the north shore 

 of White Lake from Montague down to the point where the lake opens into Lake Michigan. 

 Thence northward past Little Point Au Sable the beach is cut away except for a mile or so at 

 the mouth of Silver Creek near Benona. North of Little Point Au Sable the beach extends 

 eastward along the south shore of Silver Lake and returns northwestward along the north shore 

 to Lake Michigan, keeping a mile or so inside the limits of the Glenwood beach. The beach is 

 then cut away for a short distance in northwestern Golden Township, Oceana County, but runs 

 eastward through southern Pentwater Township to the head of Pentwater Lake. It then runs 

 northward through the eastern part of Pentwater and follows the western slope of a till ridge 

 northward into Mason County, passing east of Bass Lake and coming back to the shore of Lake 

 Michigan immediately north of the shore of Bass Lake. It is then cut away northward as far 

 as the mouth of Pere Marquette River but reappears in the eastern part of Ludington between 

 Pere Marquette and Lincoln rivers and continues northward along the east side of Big Sable 

 Lake to the head of the lake. It then runs northward to the shore of Lake Michigan in south- 

 western Grant Township. Farther north no traces of it have been found and it appears to have 

 been overridden by the moraine that comes out to the Lake Michigan shore in the northwestern 

 corner of Mason County. 



STRUCTURE. 



In general the Calumet beach is gravelly, though in places it becomes rather sandy. Imme- 

 diately east of Bass Lake in southwestern Mason County a series of parallel ridges, which give 

 it unusual strength, appear to have been built across the mouth of a bay that there extended 

 eastward through a gap in the till ridge. At Ludington the beach is rather disjointed and frag- 

 mentary, though at certain points, as at the crossing of Ludington and Washington avenues, 

 it is clearly denned. Its poor preservation makes it difficult to estimate its general strength, 

 but it seems on the whole to be about as strong in its northern part as it is near the outlet, where 

 its strength compares favorably with that of the Glenwood beach and indicates a lake stage of 

 considerable duration. The Calumet appears throughout its course as a single ridge and a 

 strong one. 



TOPOGRAPHY. 



The Calumet beach, like the Glenwood, is somewhat higher for a short distance in the north- 

 ern portion of the eastern shore than it is in the southern end of the Lake Michigan basin. Spirit 

 levels run at Ludington by J. A. Mitchell, county surveyor, show the crest of the beach, at 

 the crossing of Ludington Avenue near Washington Avenue, to be 636 feet above sea level or 

 about 56 feet above Lake Michigan. The strong beaches near Bass Lake were found by Gold- 

 thwait to be 46 to 48 feet above Lake Michigan or 627 to 629 feet above sea level, and a weaker 

 ridge between these strong ones and the lake is 38 feet above the lake or 619 feet above sea level. 

 The altitude at Muskegon is about 46 feet above the lake as determined by Goldthwait, or 

 627 feet above sea level. In Muskegon there are indications of shore action at 33 to 35 feet 

 above the lake. The remainder of the shore to the south seems to be but 35 to 40 feet above 

 the lake or 615 to 620 feet above sea level. 



Reference was made in the discussion of the Glenwood beach to channels cut across the 

 large deltas formed by the Grand River outlet near Zeeland and in Allendale Township, Ottawa 

 County. These channels appear to be in harmony with the Calumet beach, their floors being 

 within about 5 feet of the level of that beach. The channels on the Allendale delta are appar- 

 ently as high as the Calumet beach, but the one in the delta at Zeeland seems to be a few feet 

 lower. The channel that leads to Zeeland is, however, filled by peaty accumulations a short 

 distance above Zeeland to a level fully as high as the Calumet beach, and it nowhere seems 

 low enough to be in harmony with the next lower or Toleston beach. 



