244 REVIEWS. 
part first. The second part of the volume is taken up with chap- 
ters on the mineralogy, lithology and chemistry. In the appendix 
is a catalogue of the birds of the state contributed by Mr. J. A. 
Thongh the survey was cut short by the mistaken policy of the 
state legislature, many valuable results were obtained that demon- 
strate the necessity of a still more detailed survey in the future, 
as the geologist was obliged to suspend work, just as important 
discoveries of direct value to the state seemed to be imminent. 
Among the results thus far attained however, is the “ satisfactory 
solution of the question as to the relative position of the strata 
that underlie and overlie the coalbearing formations, and the de- 
terminations of their dips and trends. As a result of this, the opin- 
ion is confidently expressed that coal may be sought for over the 
whole of Southwestern Iowa with reasonable hope of finding 
plentiful supplies at a not unusual depth as mined in other coun- 
tries and in other parts of our own. Thus we have reason to hope 
that -the present known coal area of the state, amounting to 
about seven thousand square miles, will be doubled by the discov- 
ery of coal at some depth beneath the surface of an equal area of 
Southwestern Iowa.” The existence of large quantities of excel- 
lent peat and gypsum are indicated, and the survey demonstrates 
the value of some of the magnesian limestones for the preparation 
of hydraulic lime. 
The work is evidently thoroughly done and the details presented 
in a clear and systematic manner. The geological map-model, 
facing page 32, is most excellent in its plan and one which will 
prove of great use in lectures. The different rock formations ap- 
pear in relation to each other and in their relative extent just as 
they do in nature. We trust the state may yet finish the work so 
well begun, and that the fossils, ang animals and plants of Iowa 
may be described and figured. 
Tae Gereorocy or Micnrean.* —In his report of progress Prof. 
Winchell gives an interesting sketch of his projected final report. 
Should the state finish the survey, which can be done in two 
years, the publications of the results will be invaluable for the 
future development of this rich and influential commonwealth. 
*Report on the Progress of the State Geological Survey of Michigan. By A. Win- 
chell, Director. Lansing, 1871. 8vo, pp. 64, 
