58 OIL AND GAS; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
so that in most of this territory the mapping has been done from 
measurements made directly to the sands, thereby avoiding the use 
of the less accurate convergence sheet. For this portion of the 
quadrangle the map is probably almost as correct as the scale and 
contour interval will allow. For the southeastern and southern parts 
of the quadrangle the result is far less accurate, owing to the scarcity 
of wells and also because of the rapid and very unequal change in 
distance between the Gordon sand and the surface rocks, which 
renders the convergence sheet of little aid in working out the struc¬ 
ture of the underground beds. In this portion of the sheet the gen¬ 
eral features are correctly represented, but an implicit dependence on 
the details as shown is not to be encouraged. In an area of this kind 
there are always more or less conflicting data, and the small struc¬ 
tural features shown on the map simply represent the preponderance 
of evidence. However, it is believed that the map is sufficiently 
accurate to be of great value in drilling that portion of the quadrangle 
which still remains untested. 
DESCRIPTION OF OIL ANO GAS POOLS. 
WASHINGTON-TAYLORSTOWN OIL POOL. 
The Washington-Taylorstown oil pool, together with its extensions 
to the south and southwest, embraces the entire productive area of 
the quadrangle, with the exception of a group of three small pro¬ 
ducing wells about 1 mile south of Point Lookout, with which this 
pool seems to have no direct connection. As may be seen from the 
map (PL XIII), one or more of the three groups of producing sands 
previously mentioned contain oil in the bottom and along the sides 
of the northern portion of the Finney syncline in a continuous belt 
from Washington to a point within half a mile of Claysville, and 
southward along the eastern slope of this trough to and around the 
nose of the Washington anticline, near the low saddle on Tenmile * 
Creek. In this basin are finely revealed the conditions set forth on 
PL I (p. 16). More or less salt water is found in all the sands, but in 
no two is it at the same level. In each sand the lower edge of the 
productive belt lies directly above the top of the salt water in that 
bed, and, so far as the records reveal it, this line is practically hori¬ 
zontal. The upper limit of the productive belt in each bed is parallel 
to the lower edge only in a general way, the width of the belt being 
governed apparently by minor structural features and the dip, 
thickness, and porosity of the sands. 
It will be seen from PL XIII (pocket) that the productive area of 
the Gordon sand lies in a broad belt around the steeply pitching crest 
of the Washington anticline at Washington and along the northern 
