Stratigraphy of Bituminous Coal ield.— Stevenson. 353 
geological survey, is merely a more extended bit of work like 
that done for the Ohio state line in Pennsylvania. 
This synopsis of the bituminous coal field is no mere com- 
pilation. Prof. White's work began in 1875, when, asthe writer's 
aide on the 2d Pennsylvania survey, he worked out the highest 
rocks of the Appalachian area, and secured the knowledge which 
has made him an authority on the series above the Pittsburgh 
coal bed; afterwards he unraveled the tangle along the state 
line; his economic investigations in later years compelled the 
underground tracing of the beds in oil-borings and the study of 
outcrop lines and cross sections in West V'rginia far more in de- 
tail than could be required under ordinary conditions. To utilize 
his material it was necessary to connect with the Ohio survey and to 
make use of its work. The compact statement before us presents 
the summary of facts obtained during fifteen years of field work. 
The author's division of the Carboniferous into 
Upper, with alternations of fresh and brackish water, 
Middle, with alternation of marine and freshwater conditions, 
Lower, wholly marine. 
answers well for the greater portion of the Appalachian area and 
appears to answer, with rare exceptions, for the region under con- 
sideration, the only exception being in southwestern Pennsyl- 
vania, where marine fishes found their way far north at a late date; 
but this cannot be regarded as militating against the general con- 
ditions described by Prof. White. The memoir treats only of the 
Upper and the Middle Carboniferous, waicn are divided into ;— 
XVI. Permo-Carboniferous—Dunkard Creek series. 
XV. Upper Coal Measures—Monon ahela River series. 
XIV. Barren Measures—Elk River series. 
XIIL. Lower Coal Measures—Allegheny River series. 
XII. Pottsville Conglomerate. 
The line between Middle*and Upper is drawn almost midway 
in XIV, the Lower Barren Measures of the older geologists. The 
grouping is that presented by the Rogers brothers more than half 
a century ago. 
A chapter is devoted to each series, in which Prof. White gives 
a resume of characteristics of the series as a whole, which is fol- 
lowed by vertical sections, so numerous and in such detail as to 
leave no room for doubt as to the accuracy of the identifications. 
The last portion of the chavter describes the more important mem- 
bers of the series. 
