26o TJie American Geologist. April, i898 
the whole series of phenomena become concordant and consistent and in 
the question of the presence or absence of a distinct sub-Aftonian till 
sheet the beds to be considered lie all at one horizon — below the gravels. 
There are certain concordant phenomena which must be kept in mind 
in framing a hypothesis to explain the Afton exposures. The gravels 
themselves are exposed at several points. A peat bed is found in wells 
near Afton, and forest beds are found near Lamoni, Murray, Fon- 
tanelle, Washington, Sigourney, and at various points in Taylor county, 
Iowa, and Harison county, Missouri. The peculiar blue black bowlder 
clay is occasionally exposed throughout the state. There is a gumbo 
between drifts at points in Clarke and Decatur counties, and an old 
soil shows on Grand river. The exposure near Hastie, in Polk county, 
is considered very significant. 
Sian?/iary. 
In considering the conclusion to be drawn from the evidence now in 
hand the remarks relative to the value of the various lines of evidence 
should be kept in mind. 
First. It is submitted that there is widespread evidence of buried 
forest and peat beds in the region. It is admitted that nothing of im- 
portance bearing on the character of this flora as regards climate is 
known. It is further admitted that these notes on forest beds have not 
been sifted and much of the evidence is of uncertain value. It is on 
the other hand to be noted that certain of the beds are well attested 
as to position, occupying a horizon fitting well with the hypothesis of 
two drifts and that some are of a thickness worthy of consideration. 
Tpon the whole, however, the argument from forest beds probably has 
iittle independent value. 
Second. Buried soils have been shown to be not unknown, though 
the value of the evidence derived from them is uncertain. 
Third. It has been impossible so far to apply the ordinary tests 
based on leached and ferretto zones to the sub-Aftonian. 
Fourth. Waterlaid beds are present at several points at the Aftonian 
horizon. In Polk county they are believed to be notably earlier than 
the overlying drift. At Afton they seem to the writer to represent 
kame-like aggregations made during the advance of the Kansan. In 
general the waterlaid beds are such as might have been formed by 
agencies closely connected with the ice. The possible exception is the 
buried loess at Afton Junction which, however, would only necessitate 
a considerable change in the vigor of deposition between the time of its 
formation and the laying down of the overlying 8■ra^'el. 
Fifth. Since the presumed sub-Aftonian drift is thought to be 
wholly covered by the Kansan and is certainly known to be in the 
region studied, there is but little chance to contrast the topographic 
development of the two drift surfaces. Relative to erosion in the 
period between the two drift sheets it may be stated that the Hastie ex- 
posure strongly favors such a supposition. In considering the matter 
whether or not the exposures near Afton also favor such an hypothesis 
