REVIEWS 519 
as itwas being overridden, became the basal part of the ice and 
exhausted to a degree its transporting capacity, forming the effective 
load of the natural stagnation zone at the base of the ice. Over a rock 
surface, on the other hand, the ice may have possessed its maximum of 
transporting and abrading power. 
A unique detail in the drainage of Humboldt county is the practice, 
reported of draining kettle-hole lakes in certain districts by sinking 
wells through impervious layers to a porous stratum. The method 
appears to be effective and economical, though its sanitary bearing 
upon the drinking water of the region may be worthy of consideration. 
A notable feature of Mr. Beyer’s report on Story county, also of 
Professor Udden’s on Muscatine county, is the determination of defor- 
mations. The gentle flexures, of which the Skunk River anticline is a 
type, are suggestive when considered with similar structures which have 
been reported at many points in the exposures of different formations 
across the upper Mississippi basin. The reiterated recognition of such 
structure suggests that the phenomena of crustal shortening have been 
restricted by no means to the mountain belts of the coastal regions 
but that these gentler flexures, affecting such immense areas, may have 
been, inthe aggregate, an equally notable factor in the adjustment of 
the external masses of the earth to internal changes. 
Mr. Beyer gives an excellent report on the stratigraphy, including 
many valuable well records. ‘The discussion of the development of 
the Skunk River system is an instructive physiographic study. The 
course of the pre-Wisconsin channel, the transference of much of the 
Skunk River drainage area to the Des Moines system by the Wisconsin 
invasion, the post-glacial struggle of the stream toward readjustment, 
form the substance of a finely developed discussion. Remains of the 
Mammoth are reported by Mr. Beyer from an excavation four or five 
feet below the surface of the Wisconsin drift. Coal, clay and building 
stones are the economic products of Story county. 
The report on Muscatine county by Professor Udden is characterized 
by carefully derived conclusions and is rendered thoroughly readable 
by the excellent style of presentation, and enjoyable by the variety of 
new and sharply observed phenomena. ‘The stratigraphy of the county 
includes the Gower stage of the Niagara, Wapsipinicon and Cedar 
Valley stages of the Hamilton, Sweetland Creek beds of the Upper 
Devonian, Kinderhook group of the Mississippian and the Des Moines 
stage of the Coal Measures. This article contains an exhaustive discussion 
