436 THE ILLINOIS GLACIAL LOBE. 



have been found near Pier Cove at the base of sand dunes, at a slightly 

 higher level than 60 feet, but this place was not visited by the writer. North 

 from the mouth of the Kalamazoo River only a brief reconnaissance was 

 made, so that the full extent of the beaches has not been ascertained. A 

 verv strong beach appears immediately east of Holland, on the south side 

 of Black River, at an altitude 60 to 65 feet above Lake Michigan. This 

 beach appears also in Zeeland. Evidence of wave or current action at a 

 higher altitude is found a few miles east and south of Zeeland on the 

 slopes of Covert Ridge. A wave-washed surface is found at an altitude 

 about 100 feet above Lake Michigan, in the vicinity of Vriesland, and 

 northward from there to the border of Grand River. Passing southwest- 

 ward from Vriesland a sandy belt is found at a still higher level, its upper 

 limits being about 120 feet above the lake. This sandy belt is well dis- 

 played at Overisel and Filmore Center and is traceable for several miles 

 along the inner slope of Covert Ridge. It has a definite ridging, as if 

 marking the border of the lake, but may possibly have been drifted a few 

 feet above the water level. In that case the water level here may have 

 been about the same as at Vriesland, or very nearly 100 feet above Lake 

 Michigan. Further study is necessary to a satisfactory interpretation of the 

 phenomena, since neither of the two beaches mentioned has been traced 

 into definite connection with the upper beach farther south. Possibly the 

 wave action displayed on the slope of Covert Ridge east and south of 

 Zeeland is that of a small glacial lake contemporaneous with the formation 

 of Zeeland till ridge. The general weakness of the beach would seem to 

 favor this interpretation. An alternative hypothesis would refer its high 

 altitude to northward differential uplift and make it constitute the continua- 

 tion of the upper beach of Lake Chicago. In that case the strong beach 

 standing at 60 to 65 feet would be the continuation of the Second or 

 Calumet beach of Lake Chicago. This matter is discussed more fully 

 below. 



There are extensive sand plains in Allegan County, Michigan, between 

 the Valparaiso morainic system and Covert Ridge, known as the "Pine 

 Plains," which probably throw some light upon the altitude of the highest 

 stage of Lake Chicago. The plains are traversed nearly centrally by the 

 Kalamazoo River and extend north to Rapid River. Between Kalamazoo 





