42 
OIL AND GAS; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
sands the steel-tape measurement to some other sand has been taken 
and the average distance that the Hundred-foot sand is known to be 
above or below this sand subtracted or added to obtain the interval 
for use on the convergence sheet. This method has been employed 
in the northwest corner of the quadrangle, where the Berea is the 
lowest sand reached by the drill and where the Hundred-foot sand 
is probably not present. To the recorded distance of the Berea below 
the surface in this area 190 feet has been added. This interval is 
obtained from a number of records of wells in the Steubenville quad¬ 
rangle, which show the distance of the Berea above the u red rock, 
also from records of wells in Jefferson township, in the Burgettstown 
quadrangle, which show the Hundred-foot shells or Berea sand above 
the “ red rock ” and the Hundred-foot sand below the red rock/’ 
In the McDonald pool, on the east edge of the quadrangle, and in 
the Westland gas territory, most of the oil and gas comes from the 
Gordon sand and the Fifth sand. By a comparison of a large num¬ 
ber of records from this territory, it is found that the Gordon lies 
from 195 to 220 feet below the Hundred-foot, with an average dis¬ 
tance of 210 feet, and that the Fifth sand averages 119 feet below the 
Gordon, or 329 feet below the Hundred-foot. These figures have 
been used in reducing measurements to the Gordon or Fifth sand to 
measurements to the Hundred-foot sand. 
For the northeast corner of the quadrangle better results could be 
obtained if more well records were employed in the construction of 
this part of the convergence sheet. Many wells have been drilled in 
this locality and the elevations of the mouths of most of them were 
obtained, but all efforts to procure the records of these wells have been 
without success. 
The convergence sheet is shown upon Plate VIII. This illustration 
is printed upon transparent paper, so that any new information ob¬ 
tained may be added, and the drawing then used to correct the map 
of the Hundred-foot oil sand. The data from which the convergence 
o 
sheet was made are given in detail in Part II (pp. 132-148). 
The irregularity of convergence between the Pittsburg coal and the 
Hundred-foot oil sand in the Burgettstown quadrangle, as shown on 
PI. VIII, is not favorable for detailed mapping of the sand. There 
is a difference of 200 feet m the interval between these two members. 
This could be easily taken care of were it a gradual increase from one 
corner of the quadrangle to the other, but the well records show an 
area of small interval, which extends in a northwest-southeast direc¬ 
tion across the southern third of the quadrangle, and from this area 
the coal and sand diverge in all directions. The determination of 
the exact location of the area of lesser interval is difficult. It can 
hardly be assumed that the wells have been drilled at the exact points 
