2 54 ^'/'^' American Geologist. April, is9>- 
substitute for that term when it was shown that the Aftonian soils and 
gravels preceded tte Kansan stage. Since the recognition of the Illi- 
iioian glacial stage the term has been used for the interval following the 
Kansan in publications by Chamberlin,. Calvin and Scott. No great 
objection to its continued use can be urged. In fact it is much to be 
desired that names once introduced should remain utidisturbed ; but it 
may alter all be a decided gain to Pleistocene geology to select a name 
for the interval between the Kansan and the Illinoian from some local- 
ity where true interglacial deposits are clearly intercalated between 
Kansan and Illinoian sheets of drift. Samuel Calvin. 
The Weathered Zone (Yarmouth) between the Illinoian 
AND Kansan Till Sheets. [Abstract.]* The extent of overlap of 
the Illinois glacial lobe upon the Kansan sheet of drift deposited by a 
neighboring lobe on the west is briefly considered. The question of the 
occurrence of a sheet of drift of Kansan age in the series deposited by 
the Illinois lobe is left open. 
The name Yarmouth, taken from a village standing on the marginal 
ridge of the Illinoian till sheet in southeastern Iowa, represents the lo- 
cality where the break between the Illinoian and Kansan till sheets wae^ 
first recognized by the writer (November, 1888). 
The sections showing this break are presented, there being in one 
section a peat bed 15 feet in depth containing much woody material 
and also bones of the rabbit and skunk. The latter were brought to 
notice by Mr. W J McGee in the Eleventh Annual Report of the U. S. 
Geological Survey. 
Natural exposures and well sections along the belt of overlap are 
presented which show that the development of a soil horizon and the 
leaching of the Kansan till surface is about as marked as in the Sanga- 
mon weathered zone. These exposures extend from Davenport, Iowa. 
southward to the vicinity of Quincy, Illinois, a distance of fully 100 
miles, and are found at frequent intervals throughout the portion of 
Iowa covered by the Illinois glacial lobe. Fortunately there was suffi- 
cient overlap of the Illinois lobe upon the Kansan till surface to make 
clear the interpretation that the Illinoian is a markedly younger sheet 
than the Kansan. This diflference in age was suspected to occur from a 
comparison of the maturity of valleys in the two districts; but the testi- 
mony of the weathered zone preserved beneath the Illinoian till sheet was 
necessary to confirm it. Frank Leverett. 
The Weathekkd ZoNh: (Sangamon) between the Iowan Loess 
AND Illinoian Till Shf^kt. [Abstract.]! After outlining the extent 
cf the Illinoian till sheet, the question of the application of the term 
I'uchanan to the interval between the Kansan and Iowan is discussed 
as follows: 
"Manifestly the deposition of the Buchanan gravels covered but a 
*Kea<l before the Iowa .\cadem,v of Science.s, Dec. 1897. 
fRcad before the Iowa Academy of Sciences. Doc. IXilT. 
