66 CHICAGO ACADEMY OF SCIENCES. 



The study of the beaches of this glacial lake is not sufficiently 

 complete for me to indicate its precise relations to, or points of 

 connection with, the ice sheet. My study has been carried no 

 farther north than to the line of Illinois and Wisconsin on the 

 west side and to a corresponding latitude on the east side of the 

 lake. Prof. Chamberlin's studies left the precise extent of the 

 higher beaches undetermined. Mr. Taylor's observations have 

 been confined to the northern portion of the basin, and as yet no 

 one has examined the intervening district, with a view to determin- 

 ing the limits of this glacial lake. Probably the most favorable 

 field for investigation will be found on the Wisconsin side, since 

 the extensive deposits of wind-drifted sand on the border of the 

 lake in Michigan make it difficult to determine the extent of water 

 action. The long stretches of high bluff, however, interrupt the 

 beaches so greatly that some difficulty is anticipated in making 

 precise correlations on the Wisconsin side. 



The Upper or Glenwood Beach. — This beach receives its 

 name from the village of Glenwood, on the Chicago and Eastern 

 Illinois Railroad, a few miles south of the limits of Chicago. The 

 name has been selected (i) because the beach is especially well 

 developed at that village and (2) because, being near the State line 

 of Indiana and Illinois, the name will be familiar to residents of 

 either State. 



In the Illinois portion of Lake Chicago this beach is present, 

 except for a few miles between Waukegan and Winnetka, where 

 the lake shore is now farther west than it was at the time this beach 

 was formed. In Indiana the beach is present throughout the 

 entire extent of the border of Lake Chicago in that State, being 

 nowhere less than two and in places twelve miles back from the 

 shore. In Michigan it is absent for a short distance at the "clay 

 banks," north of New Bufifalo, where the present shore stands 

 farther east than the shore of Lake Chicago. It is also absent for 

 the same reason for a few miles near the line of Berrien and Van 

 Buren Counties, north of St. Joseph, Michigan. Tracing in detail 

 the course of this beach is as follows : 



From the Wisconsin line southward to South Waukegan, 

 it stands only one to two miles back from the shore of Lake 

 Michigan, and comes out to that shore at the point where 

 the blufif of till sets in south of Waukegan. This bluff of 

 till stands above the lake level as far south as Winnetka. 

 From Winnetka a cut terrace, nearly 20 feet in height, extends 

 south along the face of the east till ridge, noted above, to its ter- 



