FORMATIONS IN SOUTHEASTERN IOWA. 291 
failed to reveal any plant remains in this deposit, and it is evi- 
dent that Dr. Owen confounded this sandstone with the basal 
sandstone of the Coal Measures which is often found occupying 
depressions eroded in the limestones. Moreover, the study of 
the region shows that while the succession represented by c, d, 
é, f of the upper series is in a general way correct for particular 
localities, the members are rather local in their development, 
and grade more or less into each other. They cannot, there- 
fore, be assigned a position equivalent to the remaining and more 
general members of the section. The brecciated limestone so 
often referred to by later writers is included under the lower 
concretionary limestone (@), though very little is said of it. 
Hall, 1855.—In the report issued in 1858," the formations are 
treated in greater detail and a fuller classification is adopted. 
The geodiferous beds are included in the Keokuk group, while 
Owen’s divisions, 6 and c of the upper series, are erected into the 
Warsaw group, so named from the town on the east bank of the 
Mississippi, opposite the mouth of the Des Moines River. The 
remaining members of the series are referred to the Saint Louis 
group as established by Shumard of the Missouri survey. 
Worthen.—In the report made by Worthen on the geology of 
the Des Moines Valley, the Keosauqua sandstone is evidently 
identified with the basal sandstone of the Coal Measures. In the 
report on the geology of Lee county referring to the brecciated 
limestone he says: ‘‘The changes in the lithological characters 
of this bed, which forms one of its most striking peculiarities, 
probably led Dr. Owen into the erroneous supposition that there 
were two distinct beds of concretionary limestone which he has 
represented in his general section with a bed of sandstone 
between.” Since Dr. Owen’s section can be verified locally, as 
will appear in the sequel, the error is clearly on the other side. 
Moreover, the magnesian limestones at the base of the Warsaw? 
group are identified with those occurring on the Des Moines con- 
taining Lethostrotion canadense, and hence unquestionably belong- 
ing to the Saint Louis limestone, a conclusion directly contrary 
‘Geology of Iowa. 
?Vol. II., Part. I., p. 193. 
