Review of lltcent (Jeological Literalure. 199 
Michigan, Huron and Ontario were originally the bed of a preglacial river 
which fiiat crossed the Ontario peninsula along the Niagara escarpment, 
aud was afterward diverted to a course by way of Long Point on lake Erie 
and the Dundas valley (as already shown by Spencer.) Each of the basins 
— Michigan, Huron, Erie and Ontario — began as two or three srauller lakes. 
Lakes Erie and St. Clair are the most recent, and were, not long since, 
united. While the author minities the action of glaciers he magailies that 
of fractures, faults aud changes of relative levels. 
Northwest KanxaH : It» Topofjrophy, Oeolotjy, Climate and Resources, by 
Robert Hay, F.G.S.A. This memoir appears to be extracted from the 
'Sixth Biennl:d Ileport of the Kansas State Board of Agriculture," pp. i»l- 
116. It is a well digested and valuable exhibit of the features of the state 
in the particulars nnd within the limits mentioned. It is noteworthy that 
this, like so many similar memoirs in various parts of the country, is the 
outcome of intelligence and enterpriso controlled by the agricultural in- 
terest. Every surveyof natural resources ought to be conducted with due 
regard to that interest; but on the other hand, that interest is recreant to 
itself when it prescribes narrow, unenlightened and miscalled "practical" 
limits to the researches of the geologist. This memoir is illustrated by 
profiles and a geologic section, and by numerous scenic photo-engravings. 
The usual blemishes of public documents printed under contract are seen 
in the absence of the proof-reader's finishing touches. It may be to the 
same cause that we are to ascribe the disregard of established usage in the 
printing, capitalizing and italicizing of the few technical names employed. 
We are aware that the stock compositors use their own sweet will in dis- 
pensing v,'ith typographic discriminations and emphasis ; but all evidences 
of either ignorance or neglect present a bad appearance in a western pul>- 
lication. 
Le» mineravx des rocfces : By Lkvy and Lacroix. 384, pp. 8vo; 13,fr 50. 
Paris, Baudry and Co., This new and advanced work on microscopic 
petrography is primarily devoted to the determination of minerals of very 
small demensions by means of mineralogical and chemical tests in con- 
nection with the microscope, and secondarily to a summary description of 
the different minerals by the application of the new methods. In their 
researches in optical mineralogy the authors have carried to a gi eater 
<Iegree of exact application the laws of polarized light and its modificatioiis 
by minute crystals when placed on tlie stage between crossed Nicols, than 
has been done ia any similar work. The different crystal systems are 
illustrated in great fulness, as th-^y exhibit their characters and extinctions 
in parallel light, and to these actual observations are applied the theories 
<)f mathematical determinatioGs. A similar exempljlication is made of the 
nse of convergent light, of refraction, and of polychroism. Another 
chapter presents a ri'8um(r; of the more recent methods of micro-chemistry 
to the qualitative analysis of minerals. Here are summarized, and some- 
times modified and improved, the processes of IJoricky, Fouqu(-, Behrens, 
Haushofer, Streng, KK-ment and Ileaard; closing with a table of the prin- 
cipal micro-chemical reactions. 
