124 The American Geologist. August, 1902. 
not failed to compass the lield in a most entertaining and yet elementary, 
style. The work is intended for the "earlier stages of the high-school 
course," and it is a masterpiece in the accomplishment of that design. 
Most of the picture illustrations, as well as text descriptions, are from 
natural scenes in the United States. Principles are drawn from concrete 
cases. Indeed, as the authors state, "the treatment, so far as possible 
is concrete." The illustrations are new and telling. In a general but 
rather thorough, examination of the book we have been impressed 
with the clearness and yet conciseness of its simple sentences. We 
have noticed but few vague or incorrect statements, and these imply 
slight errors in the understanding of the facts. On page 149 this state- 
ment is made : "The Mississippi was thus, as we have seen, forced out 
of the old open valley, at jMinneapolis, and is gradually reducing the 
grade of its new course by cutting the gorge that runs down to St. 
Paul." It should have read down to Fort Snelliiig, since the gorge 
from Fort Snelling to St. Paul is much older than the gorge which 
the river is now cutting. Also on page 67 is the statement that the 
upper Mississippi "flows in a valley between rocky but often well- 
separated bluffs. At Minneapolis it enters a short gorge," etc. As 
a matter of fact, the upper Mississippi, above Minneapolis never flows 
in a rocky, bluff-bound gorge, and it but rarely encounters the rock 
in a course of several hundred miles between its source and Minne- 
apolis, running wholly on the drift deposits. These slight errors of 
fact do not impair the force of the truths inculcated. It is, further, 
a question whether the term "glacial lakes" should be applied to the 
lakelets filling the hollows in the rnorainic belts, since it is so widely 
used to designate those extinct lakes which filled the valleys during 
the prevalence of the Glacial epoch. n. h. w. 
Western Interior Coal Field; by H. Foster Bain. (U. S. Geol. Sur., 
22nd Ann. Rept., pt. iii, pp. .131-366, 1902.) 
An admirable summary of the commercial aspects of the 'coals from 
the fields of Iowa. Missouri and Kansas is that given by Dr. Bain in 
the 30 pages of the 22nd annual report of the U. S." geological survey- 
After briefly referring to the geological distribution, the statigraphy 
and the structure, the number and extent of the workable beds are 
discussed. "In the Western Interior field the coal is very irregularly 
developed along the various coal horizons. Indeed it has so far proved 
impossible to make a general section showing even the coal horizons 
which would be of more than local value. This patchy distribution of the 
coal is not the result of later faulting or other dynamic phenomena, 
but is due to the conditions under which the coal was accumulated. 
The bulk of the coal mined, 80 to 90 per cent., is taken from the Cher- 
okee shales. From 10 to 18 per cent, is from the other divisions of 
the Lower Coal Measures. The remainder is from the Upper Coal 
Measures. The coal beds of the Cherokee shales are much more irreg- 
ular than those found higher in the series. They are also much thicker. 
They, however, thicken and thin very rapidly, varying from nothing 
to 7 feet in a horizontal distance of a few feet. The usual variation is 
from 18 inches to 6 feet. The thicker workable beds lie in basins or 
