THE GLACIAL LAKE CHICAGO. 451 



Section of beach at Evanston made in 1887. 



Feet. In. 



Yellowish-red, iron-stained sand 3 _ 5 



Band of bog iron ore 4_ g 



Gravel with beds of sand included (the stratification is very irregular in thickuess and 



assorting very imperfect) 5 _ 7 



Coarse sand, not calcareous &-\2 



Calcareous loam 3 



Yellow clay, very calcareous, with leaves embedded 3 



Carbonaceous baud, not calcareous 2 



Yellow carbonaceous clay, calcareous 4_ g 



Band of carbonaceous material, not calcareous 2 



Brown saud, with twigs and peaty material 8-10 



Water-bearing sand and talus-covered slop 8 



Height of bluff 22 



The calcareous clays of each section contain numerous gasteropod 

 shells. Dr. Marcy has collected a large number of shells from them, among 

 which there are Unios, apparently of several different species but not specif- 

 ically identified. Mr. C. T. Simpson has identified nine different genera of 

 mollusks, all of existing species, found in the peat and marl bed of Dr. 

 Marcy's section. Planorbis and Lymnsea are very abundant. Prof. D. P. 

 Penhallow has identified two wood specimens, one a new species of Picea 

 {Picea evanstoni), the other a new oak (Quercus marcyand). 1 The bone 

 of the deer found by Dr. Marcy is a portion of the femur. The writer has 

 found many localities in the sandy portions of this beach, where molluscan 

 shells abound. Nearly every exposure in the sandy district west of the 

 beach, from the main part of the city of Chicago southward to Englewood, 

 exhibits them. This beach is, therefore, in striking contrast with the two 

 higher beaches, which contain few shells or other remnants of life. 



An excellent artificial section across this beach, made by the Fullerton 

 avenue conduit, which leads from the Chicago River eastward to Lake 

 Michigan, across the north part of Chicago, is discussed above. The 

 deposit throughout is mainly sand, but some gravel was encountered. 

 Shells of Unios and other mollusks were noted at frequent intervals through- 

 out nearly the whole width of the deposit. Beneath these beach deposits 

 there is everywhere a pebbly blue clay, apparently an unmodified glacial 

 till. Some of the sewer ditches in Hyde Park, west of Grand Boulevard, 

 have reached peat deposits below sand, at a level a few feet above the 

 lake. Wood has often been found in the sand west of this beach in Chicago. 



'Trans. Eoyal Soc. Canada, 1891, pp. 29-32, PI. II. 



