382 
SOUTHERNMOST KANSAS TILLS 
The till-like character of the deposits tends to argue against their 
being outwash materials. It is possible, although not probable, 
that the deposits owe their position to the melting and depositing 
of debris-laden ice-bergs which floated either on a marginal lake 
or else in the current of a glacial stream. That ice-rafted bould¬ 
ers are common is known to all glacial geologists. Till-like de¬ 
posits having a similar mode of origin are questionable, or at 
least none are on record so far as known to the writer. 
A fourth explanation of the till-like deposits is that they repre¬ 
sent pre-Kansan, or Nebraskan, drift material. The material is 
thoroughly weathered, is thin, appears to be patchy, and is found 
on the higher elevations, all of which facts point strongly to the 
presence of a very old drift-sheet. However, these characterictics 
also apply equally well to the Kansan drift as to the Nebraskan 
drift. Sufficient time has elapsed since the deposition of the ma¬ 
terial for its thorough weathering and erosion. The Nebraskan 
drift is not yet reported to appear at the surface anywhere within 
the limits of Kansas, and according to Todd, there are no evidences 
that the Nebraskan ice ever invaded Kansas. 
Although no definite conclusions regarding the origin of the 
described deposits can be made at the present time it is obvious 
that in a region as this, located in the zone of maximum exten¬ 
sion of an ice-sheet, occupied by the next to the oldest ice invasion, 
subjected to a very long period of weathering and erosion, and 
cut up at its most critical places by a wide valley, evidences of 
past glaciation must necessarily be greatly obscured. Only by the 
most detailed investigation can the exact position of the Kansas 
ice-sheet, and the Glacial history of the region be worked out. 
It is to the unendless zeal and scientific spirit of that pioneer ex¬ 
plorer, Professor Todd of the State University of Kansas, that 
we owe much of our present knowledge of the Pleistocene of 
northeastern Kansas. 
