518 REVIEWS 
conglomerates. Some of these conglomerates include silicified Niagara 
and Devonian fossils as part of the clastic materials. A few Cretaceous 
fossils have been identified. Undoubted chalk rock of the Niobrara, 
containing abundant /zoceramus labiatus, is exposed in one locality 
in association with the Dakota sandstone. 
The Pleistocene deposits are considered in detail. A new develop- 
ment from the field investigation is the demonstration that much of 
the extra-Wisconsin drift, hitherto provisionally correlated with the 
Iowan, belongs to an anomalous phase of the Kansan, which shows 
many peculiarities, near the border of the Wisconsin, due either to some 
protecting influence during the period of post-Kansan erosion, or to 
some subsequent modification referable to the presence of the loess and 
the proximity of the Wisconsin drift. The loess is called lowan inage 
and lies beneath the Wisconsin, except at some places where a thin 
mantle of it covers the edge of the latter, evidently as a recent wind 
deposit. The loess of this region is not of sufficient depth to have 
developed its own peculiar type of topography. 
The coal prospect for Carroll county is an exceedingly uncertain 
problem and, in Dr. Bain’s opinion, is to be solved only by the drill, 
and that only at large expense, chiefly because of the great depth of 
the drift. Moreover, the great distance from the known outcrops of 
coal make it possible that the productive measures may have thinned 
out altogether in Carroll county. The other mineral resources of the 
county are inconsiderable. The water supply is entirely sufficient. 
The area includes several artesian wells. 
The report for Carroll county is fairly representative of the method 
and character of the work done in the other counties and only special 
details of the other papers demand consideration. Mr. T. H. McBride, 
in the report upon Humboldt county, identifies the Kinderhook and 
Saint Louis of the Mississippian series and the Des Moines of the Coal 
Measures. The latter is covered by the glacial series, of which the pre- 
Kansan, Aftonian, Kansan, Buchanan and Wisconsin are recognized. 
The Wisconsin sheet is merely a thin veneer, conforming to the 
previously established Kansan-Buchanan topography. This is worthy 
of note in the light of other observations on the relations of recent 
drift sheets to underlying unindurated formations. The somewhat 
paradoxical inference is suggested that the ice sheet was normally less 
competent to disturb the surface of a deep formation of loose materials 
than the surface of an exposed indurated rock. A gravel formation, 
