230 ILLINOIS ACADEMY OF SCIENCE 



at Winnetka, along the east side of the ridge, which the 

 Gross Point Road follows, to a point south of Winnetka 

 where it turns west and north. South from this point 

 a low sand bar was built by the action of the waves and 

 current, almost cutting off the mouth of an embayment 

 to the west which is called the Skokie Bay. 



The second, or Calumet, beach follows closely the line 

 of the first and continues along the east side of the Glen- 

 wood bar. At this stage, when the lake was twenty feet 

 lower than at the Glenwood stage, or about forty feet 

 above Lake Michigan, a second bar was built, which 

 seems to have extended from some point northeast of the 

 present shore line, southwest to the Eose Hill Cemetery 

 in Chicago. This Rose Hill bar, as it is called, appears 

 at the Wilmette harbor and is followed by Ridge Avenue, 

 Evanston. Between it and the Calumet beach proper was 

 another shallow stretch of water known as the Wilmette 

 Bay. 



The Tolleston beach, the latest of the three, appears 

 at the lake on the Northwestern campus and extends 

 southwest approximately parallel to the others. At the 

 time of the formation of this beach, the lake stood about 

 twenty feet above the present lake level. Several 

 slightly lower ridges and the Tolleston bluff are men- 

 tioned by Goldthwait, but these do not appear in the 

 territory covered. 



Finally the lake fell to the present level and is now 

 causing the destruction of the land which was formerly 

 part of its floor. It seems evident that it has already 

 worn away a large amount for it is cutting into the old 

 morainal clay of the upland between Winnetka and 

 Waukegan, all traces of the three beaches having been 

 entirely obliterated. The Tolleston beach, indeed, has 

 been destroyed between Evanston and Waukegan. 



B. TOPOGRAPHY 



In general, then, the topography is that of a fairly 

 level plain, sloping from the foot of a bluff at the north- 

 west and interrupted by sand ridges parallel to the bluff. 

 At the north is the morainic upland, descending in per- 



