GENERAL GEOLOGY OF BURGETTSTOWN QUADRANGLE. 43 
of least interval; nor is it probable that the convergence is regular 
between these wells and adjacent wells. 
As has been stated, the area of small interval is in the southern 
third of the quadrangle. As determined, it extends from the vicinity 
of Cross Creek village in a southeasterly direction toward Hickory, 
and thence on to T\ estland. The data for this location are furnished 
by four complete records of the following wells: Well No. 832 shows 
a distance of 1,748 feet between the Pittsburg coal and the ITundred- 
foot sand; well No. 630, an interval of 1,747 feet; well No. 649, an 
interval of 1,750 . feet, and the Parkinson well, No. 661, 1,760 feet. 
These records are given in detail on pages 137-141. 
It will be noted that in the Miller well (No. 630) the Thirty-foot 
sand occurs at a distance of 100 feet below the Hundred-foot, and 
the Fifth sand at a depth of 419 feet below the Hundred-foot. No 
Gordon sand was noted in this record. In the Lyle well (No. 649), 
drilled by the same company, the Thirty-foot sand was found at 101 
feet, the Gordon at 320 feet, and the Fifth at 430 feet below the 
Hundred-foot sand. These records show an excess* in the interval 
between the Hundred-foot sand and the Gordon sand of about 100 
feet. This would indicate that the Hundred-foot sand has risen in 
the general section, reducing the interval between it and the Pitts¬ 
burg coal and increasing the interval between it and the Gordon sand. 
This fact„ if proved, would be interesting, but for the reason that few 
wells have been drilled below the Hundred-foot sand there are not 
sufficient data to establish it. 
The increasing interval to the northeast from the Pry, Miller, 
and Lyle wells is not a sudden break, but a gradual increase; not 
probably as regular as is represented by the convergence sheet, but 
with some degree of regularity. This is shown by a line of wells 
through the Burgettstown oil field from Cherry Valley to the valley 
of Burgetts Fork. In these wells the distance from the Pittsburg 
coal to the Hundred-foot sand increases to the northeast. 
OIL AND GAS SANDS. 
Below the surface of the Burgettstown quadrangle are found most 
of the sands from which oil and gas have been produced in western 
Pennsylvania. The Murphy sand, although probably present, is 
not mentioned in the well records examined and has produced no 
oil or gas within the area. The first two sands below the Pittsburg 
coal that are noted in the well records are the Little and Big Dunkard 
sands. They are not productive in any portion of the Burgettstown 
quadrangle and are noted in but few of the well records. These 
sands are the equivalent of the two parts of the Mahoning sandstone 
