30 
OIL AND GAS; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
recorded, the error of the string measurement would be known and 
could be adjusted back through the other formations. 
CONVERGENCE BETWEEN BEDS. 
In the Steubenville quadrangle the sandstones of the Allegheny 
formation are present, but since they have produced no oil or gas 
little attention is paid to them. The Salt sand and Big Injun are 
the formations usually noted in the records. 
A feature of great importance to those interested in making a map 
of the Berea sand is the varving distance between it and the Pitts- 
burg coal. To illustrate this and show where it takes place, the 
records of six wells have been plotted and are shown on PI. IV. 
These wells are located in nearly a straight line across the quadrangle 
from north to south. The first Avell (No. 11°) is one-half mile west 
of Knoxville. The second well (No. 53) is a little more than 1 mile 
south of the first. The third (No. 114) is 3 miles south and a little 
east of the second. The fourth well (No. 407) is nearly 7 miles in a 
direction south by a little east from the third. The fifth well (No. 
4G6) is out of line, being 5 miles in a southwest direction from the 
fourth. The section of this well is included for the reason that it 
shows the limestone at the top of the Big Injun sand. The sixth 
well (No. 479) is at Wellsburg, 44 miles south and a little east of 
well No. 407. The records are so placed that the position of the 
Ames limestone is on a horizontal line. 
The position of the Ames limestone is not noted in the records of 
these wells. Its elevation, however, was determined by outcrops close 
to the wells. In well No. 11 the top of the Berea sand is 1,113 feet 
below the Ames limestone. This distance increases in each well to 
the southeast across the quadrangle, being 1,405 feet in well No. 479. 
This shows an increase in the interval between the Ames limestone 
and the top of the Berea sand of nearly 300 feet. This change is 
mostly accounted for by the increasing interval between the top of 
the Salt sand and the bottom of the Big Injun sand. As previously 
stated, an unconformity exists at the base of the Salt sand. In the 
northwestern part of the quadrangle all of the Greenbrier limestone 
and part of the Pocono or Big Injun sand had been removed by ero¬ 
sion prior to the time of the second deposition; in the southeastern 
part some of the limestone and all of the Pocono sandstone remain. 
An allowance for this difference of interval between the kev stratum 
and the producing oil sand must be made in determining the structure 
of the oil sand. This has been done by means of the convergence 
sheet shown in PI. V. 
“ The numbers given in connection with references to wells indicate the corresponding 
numbers on the maps. 
