220 Transactions of the Academy of Science of St. Louis 
ments. Overlying the drift there was loess which Leighton be- 
lieved to have been deposited probably at two different stages, 
presumably the Sangamon and Peorian. Leighton recognized 
that it was possible that the drift was of Illinoian age, but was 
inclined to consider it of earlier origin, and suggested that it 
might be of Kansan age. 
In 1923, Leverett'® presented data before the Geological 5o- 
ciety of America which had led him to the concl:sion that the 
Nebraskan ice front in Illinois extended some distance beyond 
the Illinoian ice front. Some of the evidence was based upon 
the presence of erratics at positions that would be impossible to 
ascribe to ice-rafting or any means of transportation except ice. 
The drift itself, he believed, had been removed during the very 
lengthy post-Nebraskan time. Leverett’? reiterated this idea in 
1924, and in a letter to the writer, dated March 25, 1936, 
indicated that he still retains the belief. 
The writer reexamined the drift in the quarry of the Illinois 
Sand and Materials Company at Alton, described by Leighton 
(Fig. 19). It seems to be far more weathered than the [linoian 
till only a few miles away. 
Erratic cobbles and pebbles have been observed in severa! 
places along the Mississippi River bluffs in Jersey County, Illi- 
nois, specifically at Elsah and Grafton. From the location of 
these pebbles and cobbles it is questionable if they were trans- 
ported to their present location by streams from the Illinoian 
ice border. And their location is such as to make ice-rafting 
most improbable. 
PRE-ILLINOIAN DRIFT IN LINCOLN AND 
ST, CHARLES COUNTIES AND THE 
IMMEDIATE VICINITY 
Drift of Kansan age is found in considerable. quantities in 
Lincoln County, Missouri. The coarse glacial deposit in the 
