430 Review of Recent Geological Literatwe. 
All the important coal-beds of Colorado lie in one or the other of two 
great belts wliich cross the state from nortli to south. The most easterly- 
lies along the foot-hills of the mountains; and in this are located the mines 
of Erie, Franceville, Canon City, Walzenburg, Cucharas, Trinidad, the 
Raton mountains, &c. These coals however are inferior to those of the 
western district. The latter district develops good workable coal on the 
San Juan and its tributaries, but the most valuable deposits occur north 
of the Gunnison. In the North Fork and at Irwin begins a coal field 
which reaches north to and beyond the Union Pacific railroad, and west to 
the Wasatch. In some places 40 to 50 feet of workable coal may be seen 
in a single section. The quality will compare with any known in the 
world. It varies from hard and bright anthracite to semi-bituminous, 
bituminous and open burning coals, all equal to eastern varieties. 
Incidentally Dr. Newberry is led to remark that "the true Laramie 
group is distinct from the so-called Laramie of the upper Missouri, named 
by Hayden the Fort Union group, and which, in my [his] judgment, should 
be considered the basal member of the Tertiary." A memoir on the Fort 
Union flora will soon appear. Prof. L. F. Ward's " Synopsis of the Flora 
of the Laramie Group " really contains few of the Lower or true Laramie 
plants, and is chiefly descriptive of the Upper Laramie or Fort Union flora. 
Petroleum and Natural Gas in New York state. By Charles A. Ash- 
burner, M. S., C. E. 8vo, pp. 54, with a colored map, sections of wells, and 
a map of the Allegheny oil and gas district. A paper read before the 
"American Institute of Mining Engineers," Duluth meeting, July, 1887; 
revised to June, 1888. This important memoir contains interesting com- 
munications from Prof. Charles S. Prosser, of Cornell University, who has 
carefully preserved numerous well records of Ithaca, Clyde, Wolcott, Syr- 
acuse (State well), and supplied instructive sections (partly from surveys 
of Prof, II. S. Williams). Mr. Prosser finds the thicknesses of formations 
in central and western New York generally underestimated. 
Glaciation : Its Relation to the LackawanrM - Wyoming Region. By 
John C. Branner, Ph. D., State Geologist of Arkansas. 8vo, pp. 18. 
(From the "Proceedings and Collections of the Lackawanna Institute," 
vol. i.) This is a condensed discussion of the facts connected with the 
drift, and of the theories propounded to explain them. It contains three 
handsome artotype illustrations and two wood-cuts. It is a presentation 
well adapted to stimulate inquiry among the young, and especially in the.. 
Lackawanna- Wyoming region. 
The Jordan — Arahah and the Dead Sea. By Israel C. Russell, of the 
V. S. Geol. Survey, pp. 16. (Extracted from the " Geological Magazine," 
Aug. and Sept., 1888.) This is a connected and systematic digest of all 
which has been published on the natural features of the Dead Sea basin. 
Mr. Russel's object in this research was to in^^titute comparisons with the 
" Great basin " in America, He finds many corresponding features. 
Microscopical Physiography of the Rock-making Minerals. An aid to 
the microscopical study of rocks. By PI. Rosenbusch. Translated and 
abridged for use in schools and colleges by Joseph P. Iddings, U. S. Geo- 
logical Survey. Illustrated by 131 wood-cuts and 26 plates of photomicro- 
