410 
POPULAR SCIENCE REVIEW. 
modes of occurrence of tlie various economical substances met with during 
the work of the survey. This is well shown in the elaborate report of the 
territories, embracing Colorado, by Dr. F. V. Hayden, embodying the 
results of the exploration for the year 1873 by himself and his colleagues, 
and adding another valuable contribution to our knowledge of the geo- 
graphy, geology, and natural history of an interesting portion of the United 
States. In fact, the publications connected with this survey since its com- 
mencement in 1867 already form a large library of works relating to the 
various branches of natural history of those parts of the region which have 
been surveyed. Fully illustrated with maps, sections, and plates, this 
volume contains the geology of the east slope of the Colorado range of the 
Rocky Mountains, of the Middle and South Park divisions of the State, and 
a report, by Mr. Endlich, on the mining districts of Colorado, with a cata- 
logue of the minerals and the geology of St. Luis, in which district occurs 
distinct varieties of granite, forming the higher portions of the eastern edge 
of the front range, and is partially covered by volcanic rocks in the eastern 
and northern half of the district. The Palaeozoic rocks are fairly repre- 
sented, the Carboniferous being well developed, showing great uniformity in 
the groups of strata. A wide gap now follows, but the cretaceous strata 
are well defined, followed by the doubtful lignitic beds, which seem “ to be 
of an age which can palseontologically be referred neither to the cretaceous 
nor to the tertiary,” and above these are the tertiary, diluvial, and alluvial 
deposits. The second part contains an important chapter, by Professor 
Lesquereux, on the lignitic formations of the West, in which he still main- 
tains their tertiary character, and refers them, from personal examination of 
the localities, to four periods — Lower and Upper Eocene, and Lower and Upper 
Miocene — and describes under each group the affinities of the plants with 
those found in the Arctic, Mississippi, and European floras of either Eocene 
or Miocene age. The same part contains a report on the vertebrate palaeon- 
tology of Colorado, by Dr. E. Cope, from the formations which represent 
the cretaceous and tertiary periods. The third part is devoted to a descrip- 
tion of the collections of Invertebrata made during the survey of 1873, 
chiefly by Lieut. W. L. Carpenter. The last part includes the geography 
and topography, by Messrs. Gardner and Gannett, with a list of the eleva- 
tions of certain datum-points on the great lakes and rivers and in the Rocky 
Mountains. The “ Bulletin ” contains some interesting notes by Dr. Hayden 
on the surface features of the front range of the Rocky Mountains, which in 
the eastern ranges present a great variety of forms resulting from erosion, 
due partly to the effects of the glacial period and the subsequent combined 
action of water and ice ; but it is possible that the great Rocky Mountain 
range was outlined in form far back in the past, perhaps even during the 
carboniferous period, though it received vast additions during the cretaceous 
and tertiary epochs. Professor E. T. Cox’s report is a continuation of the 
progress of the survey of the different counties of the State, to which is 
prefixed a report on the iron and coal mining as exhibited in the last Vienna 
Exhibition. 
