32 
OIL AND GAS; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
urement to the Berea. The log, therefore, was not considered in 
making the convergence sheet. 
Log of Sophie Wright well (No. J t 88). 
Top. 
Bottom. 
Feet. 
850 
Feet. 
1,160 
l f 490 
1,510 
1,790 
No Hundred-foot sand. 
No Thirty-foot sand. 
No Gordon sand. 
2,150 
fin n Hi ft li .. ....... 
2 ,205 
2,215 
2*225 
No other data have been discarded in forming the Steubenville 
convergence sheet. Wells have been selected so as to control the 
territory as well as possible. Those whose mouths were near some 
known stratum were selected so as to avoid any error in the inter¬ 
val which might arise from incorrect contouring of the surface 
structure. 
The convergence sheet is the key to the map of the underground 
stratum, and should be studied carefully by anyone intending to 
use the map of the oil sand. The result in the Steubenville quad¬ 
rangle is considered fairly satisfactory. The wells are evenly dis¬ 
tributed over the sheet and produce isochor lines that are fairly 
regular. The distance between these lines increases regularly to 
the southeast. In one portion of the map, however, the isochor lines 
are too close together for good results on the lower sands. This 
area lies in the northeast corner of the quadrangle, over the Turkey- 
foot oil pool, and extends to Ohio River across the south slope of 
the new Cumberland anticline. Here the increasing divergence is 
nearly 50 feet to the mile. An increase at this rate would require a 
large-scale map and many check wells to obtain accurate results on 
the lower sands. 
In the construction of the map of the Berea sand of the Cadiz 
quadrangle ° a convergence sheet, governed along the east edge by 
the records of wells Nos. 221 and 228 of the present report, was 
used. 1 he difference in interval at these two wells was divided pro¬ 
portionately over the distance between them. Since that map was 
made two other wells (Nos. 145 and 402) have been drilled in the 
Steubenville quadrangle near the line of the Cadiz quadrangle, 
i hese Wells show that the interval increases more rapidly at the 
south than at the north. Owing to this new information, the con- 
n Griswold, W. T.. The Berea grit oil sand in the Cadiz quadrangle, Ohio: Bull. U. S. 
Geol. Survey No. 198, 1902, PI. I, 
