DISTRIBUTION AND VERTICAL RANGE. 39 
another (many of them are probably referable to washouts) as to render 
it worthless. Portions of the “ Pittsburg” bed in West Virginia have 
been found so thickly intersected thereby that mining operations had to 
be abandoned in such areas. While they infest some districts, others, 
fn ‘ock Islang, 
C.V. °Fort Wayne. 
Columbus. 
° 
ce 
a 
Figure 5.—Distribution of Clay-veins (C. V.) as observed in Coal Seams of the United States. 
without any apparent reason, are comparatively free from them. A glance 
at figures 6 and 7* will give a fair idea of their distribution in localities 
where they are quite numerous, or fairly so, but the thin and irregular 
offshoots are not shown, because they are far too abundant to survey and 
map. Hence only the more prominent veins are plotted. 
VERTICAL RANGE 
By way of proof that clay-veins are not confined to the seams of coal, 
cases might be cited where they have been cut in the sinking of wells, 
air-shafts, slopes, etcetera. In connection with the mining of the Pitts- 
burg coal in Pennsylvania, an air-shaft having a vertical height of 35 
feet was sunk through a clay-vein at Grant, in that State. Clay-veins 
extending upward from the coal through the overlying rocks to the sur- 
face soil were laid bare at the mouth of the Forest Hill mine near West 
Newton, Pennsylvania, a few years ago. The same veins could be seen 
traversing, in a divided form, the floor of the seam, as well as the lime- 
stone below it. These facts demonstrate the existence of clay-veins, 
*This figure was reduced from a plan of the mine kindly supplied by Albert M. Campbell, 
BE. and B. M., of Charleston, West Virginia. The locality is 175 miles southwest of the area shown 
in figure 6. 
