28 
OIL AND GAS; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
Lower Kittanning coal below the Ames limestone was determined bv 
direct measurement only in a few places. By comparison, however, 
of the elevations of other coals of the Allegheny formation at some 
places with the elevation of the Ames limestone and at others with 
the elevation of the Lower Kittanning coal, the interval was found 
to be 473 feet. The probable error of this determination is less than 
10 feet. 
A number of direct comparisons of the elevations of the Ames 
limestone and the Pittsburg coal were made. At other places the 
interval between these beds was ascertained by comparing the eleva¬ 
tion of a given point on one stratum with the elevations of two eft 
more points on the other stratum. This interval was measured at 32 
different places, with an average result of 219 feet. The largest inter¬ 
val obtained was 231 feet and the smallest 201 feet. 
The Meigs Creek coal outcrops in three-fourths of the quadrangle. 
1 he elevation of thjs coal was compared with that of the Pittsburg 
coal at 24 different places, with the average result for the interval of 
103 feet. The largest interval obtained was 113 feet and the smallest 
94 feet. 
The results of these measurements of intervals between the different 
strata indicate that it is practicable to map the surface rocks of the 
Steubenville quadrangle so that the vertical position of any point 
shall not be in error more than one contour interval, or 10 feet, and 
also that this is about the limit of exactness that can be acquired when 
more than one surface stratum is used in determining the structure. 
CONTOUR MAP OF PITTSBURG COAL AND STRUCTURE. 
After reducing all determined elevations on the various key rocks 
to equivalent positions on the base of the Pittsburg coal and connect¬ 
ing by lines the points of equal elevation, the contour map (PI. Ill) 
was produced. The contours printed in green on the topographic 
base of the Steubenville quadrangle represent the surface structure. 
I he small crosses of the same color, with numbers adjacent, show at 
what point spirit-level elevations were obtained on some known 
stratum, and the crosses which are underlined show the points where 
the elevation of the Pittsburg coal itself was obtained. 
The rocks of the Steubenville quadrangle have little regularity of 
structure. They form parts of two structural basins and a portion 
of the anticline which divides them. The most prominent feature 
is this anticline, which culminates a little east of New Cumberland. 
Here the rocks rise in a dome nearly 300 feet above their general* 
position in the surrounding region. The slopes are steep to the east, 
south, and west. This feature is. named the New Cumberland 
anticline. 
