512 MORRIS M. LEIGHTON 
water” silts of various colors, including maroon, in a tributary to 
the Mississippi River near Clinton, Iowa. Although these silts 
are believed to be younger than the “‘red loam,” they help to show 
that the Mississippi has carried reddish silts at different times. 
The age of the loesses—The occurrence of the loess on the 
weathered till shows that for a long time after the deposition of 
the glacial till there was no loess in this vicinity. If the drift is 
Kansan in age, the reddish loess may be Sangamon; if, on the 
other hand, the drift be Illinoian, the reddish loess probably is 
Peorian. It is unlike any Peorian loess of which the writer knows, 
but the color does not necessarily preclude that possibility. 
The upper buff loess is leached to a depth of 5-6 feet from the 
surface—an amount not exceeding some instances of leaching of 
loess on the Early Wisconsin. However, the summit is somewhat 
rounded, favoring some slope-wash, and hence this figure probably 
does not represent the total amount of leaching. According to 
Curator Baker, one species (Pyramidula shimekii), typical of the 
Early Peorian loess,’ occurs in the collection taken from the buff 
loess but not in that from the reddish loess. The thickness is 
unusual for post-Wisconsin loess, but its proximity to the Mississippi 
makes this possibility plausible. Thus, the evidence in hand is not 
decisive as to whether the upper buff loess is Peorian or Early 
Wisconsin. If the reddish loess is Sangamon in age, the absence 
of a record of a long interval between its deposition and that of 
the overlying buff, loess would seem to tie the two rather closely 
and favor the Early Peorian age of the upper loess. 
The mammalian fossil horizon—Mr. McAdams reported the 
mammalian fossils to be associated with calcareous concretions in 
the lower part of the loess.? They occur, however, at the base of 
the loess and the top of the till. Scores of concretions were broken 
open and examined in the hopes of finding more fossil remains, but 
reward was had in but one specimen, which contained a remnant - 
of the lower portion of some tooth of an unknown mammal. A 
quarryman at Plant No. 2 reported that in the summer of 1919 a 
Formerly called Iowan loess, but recently pointed out as Early Peorian in age: 
‘The Iowan Drift a Review of the Evidences of the Iowan Stage of Glaciation,,” 
Iowa Geol. Survey, Vol. XXVI (1917), pp. 140-64. 
2 Proc. A.A.A.S., Vol. XXXII (1883), p. 268. 
