24 C. A. White on the Gevlogy of Southwestern Iowa. 
These facts are mentioned in this connection, for the purpose 
of showing more clearly the lithological contrast between the 
Coal-measure rocks and those beneath them, in addition to the 
well known facts of their unconformability, and their natural 
paleontological differences. : 
Circumstances other than those suggested by geological fea- 
tures to be examined, rendered it desirable that the resumption — 
of the state geological work should commence in the south- 
western part, so that no opportunity has yet presented itself to 
make a complete examination of the full series of Lower Coal- _ 
measure strata, since this series does not appear at all in that 
part of the State, because the streams there have not eroded 
their valleys down to it through the upper series. This remark 
holds true of all that region composed of the counties of Deca- 
tur, Ringgold, Taylor, Page, Fremont, Mills, Pottawatamie, — 
Montgomery, Cass, Adams, Adair, Union and Clarke. The 
greater part of last season’s labors were expended in these, and 4 
other counties nearer the DesMoines river, and it is to this re 
gion almost exclusively that the following remarks upon the 
Upper Coal-measures are intended to apply. The Upper Coal- — 
measure rocks are also known to be largely developed in the — 
counties of Appanoose, Warren and Madison, and in these coun- _ 
ties, along the Chariton, South, Middle and North rivers re 
localities it is known to be much more, probably from local 
ig of the strata. f 4 
Thus in Hardin county a section has been measured which — 
reaches two hundred feet in thickness, and the presumption 18 
strong that this does not represent the full series, The upper 
half of this section is a coarse fer pocemeneenrenting =e iq 
a four-foot bed of coal, all of pri with a part of the under- 
ing fire-clay is seen upon the bank of the Iowa river. _ 
he lower half is taken fron .a boring at the same locality which, _ 
