222 Transactions of the Academy of Science of St. Louis 
Mississippi bottoms near Winfield, Missouri, has been used for 
commercial gravel pits. This gravel is probably a derivative 
from Kansan drift. Leverett? and Rubey?* both state that in 
the vicinity of Batchtown, Calhoun County, Illinois, there is 
drift of Kansan age which should probably be correlated with 
the drift across the Mississippi River in Lincoln County. It 
would appear that the ice sheet crossed the present valley of 
the Mississippi in that vicinity. From personal observation, it 
appears that the Kansan drift continues southward from Win- 
field into St. Charles County. A thin layer of drift containing 
some large boulders can be traced along Missouri Highway 79 
to within two miles north of O’Fallon, St. Charles County, 
Missouri. The boulders include one of basalt, conspicuously 
striated and over a foot in diameter, and a boulder of Baraboo 
quartzite, whose dimensions exceed three feet. It would ap- 
pear from Leverett’s studies, as shown in Antev’s?? maps, (Fig. 
14), that the Kansan ice front stood essentially parallel to the 
Missouri River, but several miles north of it, in St. Charles 
or Lincoln counties, and for some distance westward. 
North of St. Charles a thickness of more than 20 feet of 
fine clay, very uniform in texture, is exposed in a cut of the 
Wabash Railroad. The upper ten feet of the clay is mottled 
brown and gray, but below this the clay is of a deep blue color. 
‘The elevation of the upper surface of the clay is 540 feet. Sim- 
ilar blue clay, at a lower elevation, may be found in Elm Branch 
Creek, a northward flowing stream near Elm Point, St. Charles 
County. The clay closely resembles the sort laid down in quiet 
pools adjacent to an ice front. 
In a tributary to Elm Branch Creek, on a farm owned by 
J. H. Ludwig, a portion of a mastodon skeleton was excavated 
- in 1935. The bones were found in the blue clay just referred to. 
Most of the skull, with the teeth, fragments of the tusks, and 
several bones, all in a bad state of decomposition, were €X- 
cavated and placed in the collections of the Department of 
Geology and Geography at Washington University. 
