Review of Recent Geological Literature. 125 
due to the fact that marine conditions ceased, never to return, in the 
Appalachian field at least, vvitli the dei)osition of the Ames, or green 
crinoidal limestone and its associated beds, midway in the Conemaugh, 
thus separating it into two divisions, of almost equal thickness, the 
lower one abounding in marine life, while the upper has nothing 
but brackish and fresh water forms. The fauna! change at this hori- 
zon is sufficiently great to warrant the separation of these two beds 
into two series, but owing to the fact that the moraine type of the 
Ames limestone is not persistent over the entire Appalachian field and 
that the litliological characteristics are very similar for some distance, 
both above and below the horizon in question it is deemed best to 
maintain the integrity of the Conemaugh formation as modified by the 
Pennsylvania, Maryland and West Virginia geologists." 
The West Virginia survey is in cooperation with the Untied Staites 
survey in the construction of a topographical map, after which it is 
designed to enter upon the detailed geological mapping of the separate 
counties. N. h. w. 
Nebraska Geological Survey, vol i, Erwin H. Barbour, state geologist. 
13 plates, and maps, 258pp., Lincoln, 1903. 
"In the preparation of this non-technical introductory report con- 
cerning the geology of Nebraska the writer has been actuated by a desire 
to anticipate the wants of citizens, and to prepare something which 
may be useful and helpful to them." 
Prof. Barbour makes it plain that although Nebraska has not and 
cannot expect to have valuable deposits of coal and of the precious 
metals, still that a geological survey posseses great utility for the state. 
Nebraska has been troubled, like most of the other western states, by 
mining excitements by which thousands of dollars have been squan- 
dered under the specious guidance of so-called "practical miners." The 
fimction of a survey is not only to point out natural resources, but 
also to point out their absence. By the latter many wild schemes that 
are foisted and fostered by false assayors or by wandering adven- 
turers, can be saved to the citizens of many a community. 
This admirable report, while a preliminary one, calculated to open 
the way for future great extension, is still so complete in its presen- 
tation of the present known geological features of the state that it 
can but be of great service to all who wish to know about Nebraska. 
It is not only a compcnd of previous investigation, but also embraces 
the results of several years of special survey by Prof. Barbour and his 
assistants. When means are provided it is planned to enter ultimately 
upon the detailed survey and description of the separate counties in 
a manner similar to the surveys of Minnesota and Iowa. This can be 
done the more quickly, as there are numerous topographic sheets located 
within the state executed by the U. S. Geol. Survey. If this report 
is an earnest of the future, Nebraska will have when completed a 
thorough and economic as well as a scientific survey. N. H. w. 
