DEPOSITS OF THE LAKE CHICAGO BASIN 



North end Northwestern University campus, near foot of Noyes Street (Plate IV). 



63 



Strata 



Deposit 



Depth 



Remarks 



X 



rx 



VIII 



vn 



VI 



v 



IV 



m 



ii 

 i 



Yellow sand and gravel 



Sand and gravel, cross bedded 



Yellow sand 



Very fine, compact silt 



Peaty, with fine sand 



Carbonaceous matter mixed with sand and 



roots 



Fine yellow sand 



Vegetable matter and fine sand interstra- 



tified 



Fine yellow sand 



Water-laid clay, oxidized in upper part.... 



Total thickness 



69 inches 

 18 

 18 

 14 

 2 



7 

 51 



18 

 67 



With shells. 

 With plant stems. 



265M " 



= 22 feet 1J^ inches. 



The top of the compact silt (stratum VII) varies but little in height above 

 Lake Michigan west of the above section, which was made on the east face of 

 the beach. Dr. U. S. Grant, has kindly measured this elevation, which is as 

 follows: 



Section on face of beach 13.57 feet above Lake Michigan 

 Twenty feet to the west 13.50 " " 

 Thirty feet to the west 13.82 " " 

 13.47 " 

 13.72 " 

 14.82 " 

 13.97 " 

 14.02 " 



Forty feet to the west 

 Forty feet to the west 

 Forty feet to the west 

 Fifty feet to the west 

 Fifty feet to the west 



It is interesting to compare this recent section of the Toleston beach with 

 the previous sections of Marcy and Leverett. 9 The two carbonaceous layers 

 (strata VI and III of the 1912 section) are repeated, and the fine silt deposit 

 contains molluscan shells. As these peaty deposits have been found in various 

 parts of Evanston, and also as far west as the north shore channel, it seems 

 evident that they represent low water periods when the surface was exposed 

 and grass and trees grew upon it. It is to be noted that the carbonaceous 

 strata of Leverett's section are closer together than in Marcy's or Grant's sec- 

 tions. 



Many years ago, Dr. Oliver Marcy, (now deceased) of Northwestern Uni- 

 versity, collected a number of shells from stratum number 7 of his 1864 section 

 (Plate IV, section I, number 4) which were identified by Mr. C. T. Simpson 



8 Pleistocene Features, p. 76. 



