GLACIAL LAKE CHICAGO. 353 



The Grand Trunk Railway survey indicates that the border of the swamp in western Ravenna 

 Township is about 660 feet above sea level, and a series of levels run by Goldthwait at Eastman- 

 ville, only 15 miles south, indicate that the strongest beach there is but 632 feet. Faint indica- 

 tions of shore action appear on the moraine north of Eastmanville in the southeast part of sec. 

 29 at about 654 feet, and ridges northeast of Dennison by Goldthwait's levels rise to 655 and 

 665 feet. The highest of these, at a gravel pit at Amos Taylor's farm, is strong and seems to 

 have been shaped by waves, yet its lack of continuity may be an indication that it is not a shore 

 feature. Before this correlation can be satisfactorily settled and the 660-foot beach classed 

 as Glenwood further studies should be made and levels run to determine whether a lower shore 

 exists at a level corresponding with the general elevation of the beach in the southern end of 

 the Lake Michigan basin, or about 640 feet. It may be remarked, however, that all the observa- 

 tions on the beach north of Muskegon indicate that its altitude is about 660 feet and that it is 

 thus in harmony with the line which follows the east border of the swamp in Ravenna and 

 Sullivan townships, Muskegon County, and with Goldthwait's levels near Dennison. 



North of Muskegon River the Glenwood beach lies along the west side of the Whitehall till 

 ridge from sec. 23, Fruitland Township, northward, the ridge itself rising nearly to the level of 

 this beach in the northeast part of sec. 36. The district east of the till ridge was probably sub- 

 merged at this time no farther north than the vicinity of Sweet station, for basins are present 

 in the gravelly plain north of that station. 



On the north side of White River a narrow till plain lying along the inner slope of Whitehall 

 tiU ridge stands slightly above the level of Lake Chicago. A ridge of sandy gravel, apparently 

 marking the shore, leads westward from the Whitehall till ridge near the north edge of Montague 

 through the north part of sec. 20 and south part of sec. 18, Montague Township, and the north 

 part of sec. 13, White River Township, to another till ridge in sec. 14. This shore has an altitude 

 of 655 feet immediately north of Montague, as determined by Goldthwait's levels, or about 5 

 feet lower than the supposed shore crossed by the Grand Trunk Railway east of Muskegon in 

 western Ravenna Township. 



Shore features are poorly developed on the west slope of the till ridge in White River Town- 

 ship, the surface being very irregular. From near the line of Muskegon and Oceana counties 

 northward for several miles the bluff of the modern lake rises above the level of the Glenwood 

 beach, some points being fully 200 feet above Lake Michigan. At Benona, where Stony Creek 

 enters the modern lake, a recess of Lake Chicago extended inland about 3 miles, covering the 

 southern edge of sees. 31, 32, 33, Benona Township, and the northwestern part of Claybank 

 Township. The upper limits of lake action are 75 to 80 feet above Lake Michigan, 655 to 660 

 feet above sea level. For several miles north of this recess the shore of Lake Michigan is again 

 very prominent. Near Silver Lake a recess extends into sees. 16, 21, 28, and 33, Golden Town- 

 ship, and north of this the Glenwood beach comes back to the shore of Lake Michigan in sec. 8. 

 Hand levels run near the line of sees. 5 and 8 show its altitude to be 75 feet above Lake Michigan 

 at a 582-foot stage, or 657 feet above sea level. 



In northwestern Oceana County the Glenwood beach runs back inland nearly to Hart. A 

 terrace on Pentwater River at Hart, altitude 655 feet, probably marks the level of the stream 

 bed . On the north side of Pentwater River j ust below the j unction of the two forks, immediately 

 east of Pentwater, a till ridge sets in which stands at about the level of the Glenwood beach for 

 several miles northward and which has its crest generally capped with sand. A bay east of this 

 till ridge apparently covered about 25 square miles of sandy plain in northwestern Oceana and 

 southwestern Mason counties, though its limits are difficult to define. 



About 3 miles north of the Oceana-Mason county line the Glenwood beach comes back 

 to the shore of Lake Michigan at an altitude, by Goldthwait's levels, of 649 to 650 feet. For 4 

 miles north from this point high bluffs mark the coming of a prominent moraine to the lake 

 shore. North of this moraine on the south bluff of Pere Marquette River lake action was found 

 to be well denned at about 660 to 665 feet. The shore from there runs eastward along the south 

 side of Pere Marquette River nearly to Scottville and then goes northwestward, passing just 

 34407°— 15 23 



