REVIEWS 93 
basic to the most acidic in composition, and from late Cambrian to 
pre-Devonian in age. These igneous rocks probably take the form 
of thick laccoliths, and the different rock varieties are arranged in the 
order of decreasing basicity. In many cases erosion has removed the 
acidic members of the series. Serpentine itself is the least abundant 
rock of the area, but the most important economically. 
Thirty-four mineral species are described from the area. In many 
cases their origin is given, especially the alumino-silicates rich in lime 
such as diopside, vesuvianite, and grossularite, which occur as dikes 
in the peridotite and are not the products of contact metamorphism. 
The CaO content for these minerals is thought to have been extracted 
by magmatic waters from the already consolidated portions of the 
igneous mass. Microscopic diamond crystals were found in the chro- 
mite, which is further evidence of the primary origin of chromite. 
Eleven new forms of diopside are recorded, with a number of illustrative 
drawings. Colerainite, H;Mg,A1SiOs, is a new mineral species found 
in Coleraine Township, and its physical properties are described in detail 
with a number of chemical analyses. The mode of origin of the various 
varieties of serpentine is described with chemical analyses. Good views 
of the pits and microphotographs are given. 
J. F. W. 
Report on Braxton and Clay Counties. By Ray V. HENNER. West 
Virginia Geological Survey, 1917. Pp. 883, pls. 29, figs. 16. 
A report on the mineral resources of the area with a discussion 
of its general geology. Aside from soils the principal wealth of the 
two counties is in the oil and gas pools, building-stone, and clay and 
shale for brick. The report is accompanied by topographic and geo- 
logic maps. 
Part I considers briefly the physiography and history of the develop- 
ment of the region. The counties are in the central part of the state, 
on the eastern flank of the Appalachian geosyncline. Their present 
topography is that of a deeply dissected plateau. 
Part II is an account of the general geology. The structure is 
simple, consisting of a gentle dip to the northwest, interrupted by 
gentle folds. The stratigraphic range is from the upper Devonian 
through the Paleozoic. Some Pleistocene river terrace deposits are 
present. A detailed description accompanied by sections is given for 
each formation present. 
