262 The American Geologist. April, i89n 
evidence, that there are in Iowa traces of a drift sheet older than the 
KaHsati and separated from it by an imkfwmn but probably considerable 
interval. 
It may be mentioned in conclusion that it has been suggested, nota- 
bly by ChamberHn,* that a complete series of deposits recording a 
glacial period should theoretically include a series of early minor ad- 
vances culminating in a period of maximum glaciation, followed by a 
second series of advances of decreasing intensity. We have for some 
time faced the anomaly that the earliest glaciation of which we had 
record was that of showing the maximum extent of the ice. The pre- 
Kansan fills in tli* gap and answers apparently to one of these earlier 
and minor stages of advance. Additional work along the extreme drift 
border may possibly prove that the pre-Kansan extends out beyond the 
Hmits of the Kansan, but this is considered improbable. It is to be 
noted that according to the theory there should be more than one pre- 
Fvausan advance and partial retreat of the ice, just as we have several 
post-Kansan ice sheets. These earlier drifts may or may not have been 
separated by notable intervals as in the case of the later drifts. It is 
quite possible that the pre-Kansan we now know of is not all one thing, 
and for this reason, as well as the incompleteness of our knowledge of 
it, it seems best that this earlier drift should not be given a definite for- 
mational name, certainly not until more is known of it. For the pres- 
ent, the term pre-Kansan may be used, and just as pre-Cambrian, in a 
much Older portion of the geological column has come to have an ac- 
cepted meaning, it is believed that the term will be valuable. The pre- 
Kansan of Iowa may or may not belong with the Albertan of Dawson. 
It may be older or younger. Probably we shall never know very much 
about its divisions, though we may justly expect to know much more of 
its distribution and character. It should be noted that the original cor- 
relation of the forest bed of eastern Iowa with the .\ftonian deposits 
proves now to be essentially correct, since the former includes deposits 
I)oth above and below the drift now known as Kansan. Possibly 
further study may indicate the advisability of a return to original nomen- 
clature, though that outcome is not thought to be probable. 
H. Foster Bain. 
Some Pregl.\ci.al .Soils. [Abstract. ]t In the region south of the 
Wisconsin driftless area an old soil is occasionally found under the 
Kansan drift, generally resting on bed rock, and often associated with 
laminated, water-bedded clay and other silt. An exposure of such a 
soil occurs under a blufif of drift in the southern part of Muscatine, 
Iowa. The material here is dark brown in color, mottled with small 
black fragments of vegetable tissue. The upper part is a dark mucky 
clay. The whole bed is only two or three inches in thickness. It lies 
below what appears to be pre-Kansan drift. A similar bed was un- 
covered on the east side of Eastern avenue at Davenport, Iowa. This 
*GreatIce Age (Geikie), p. 736. 189.i. 
tRead before the Iowa .\cademy of Sciences, Dec. 1897. 
