20 
ECONOMIC GEOLOGY OE AMITY QUADRANGLE, PA. 
well is 3,61 1 feet, or 3,186 feet below the Pittsburg coal. As the lowesl 
exposed horizon in the quadrangle 
Conemaugh , 
formation 
Allegheny J 
formation ) 
= = 
Pottsville J 
formation 
Unconformity 
Mauch Chunk 1 
formation | 
mm 
Pocono 
formation 
_ — - 
, I 
igg^i 
i hemung 
§^^=^- 
, 
Pittsburg coal 
Murphy sand 
Little Dunkard sand 
Big Dunkard sand 
Upper Freeport coal 
is only a few feet below this coal, 
the thickness of the nonexposed 
rocks in the well is about 3,15C 
feet. Most of the wells in thai 
part of the quadrangle average 
from 2,500 to 3,100 feet in depth, 
In the northwestern part they are 
shallower, averaging not more 
than 2,300 to 2,900 teet. In 
neighboring portions of Pennsyl- 
vania several deeper wells have 
been drilled. The deepest oi 
these is a well 12 miles southeast 
of Pittsburg, which penetrated to 
a depth of 5,575 feet and is the 
deepest well in the United States. 
It started 130 feet below the 
Pittsburg coal. A very deep well 
has also been drilled near Mc- 
Cracken, in the western part of 
Greene County. 
Datum horizon. — The Pittsburg 
jordon stray sand jcats- ed c0& \ } underlying nearly the entire 
quadrangle, is the most persistent 
and most easily identifiable hori- 
zon in southwestern Pennsylvania, 
and is always recognized by well 
drillers, who make their calcula- 
tions of the depth to underlying 
oil and gas sands with reference 
to it. In this report this coal is 
therefore used as a datum horizon, to which the depths of other beds 
are generally referred. 
CAKBONIFEROUS SYSTEM. 
PENNSYLVANIAN SERIES. 
ROCKS BETWEEN THE PITTSBURG AND UPPER FREEPORT COALS (CONEMAUGH 
FORMATION)- 
Definition. — The rocks known as the Conemaugh formation com- 
prise all those included between the Pittsburg coal at the top and th( 
Upper Freeport coal at the base, both coals being excluded from the 
formation. In the reports of the Second Geological Survey thest : 
rocks were called the Lower Barren Measures. 
Thickness. — The thickness of the Conemaugh formation in Penn 
sylvania varies from 500 to over 700 feet. In this quadrangle it h 
Red rock 
Big lime 
!5iK Injun sand 
Squaw sand 
Thirty-foot sand 
Red shale 
Gantz sand \Hundred- 
Fifty-foot sand J foot sand 
Gordon sand 
Fourl h ^ .- 1 1 1 < 1 
liiih Band 
Bayard sand 
Elizabeth sand 
Fig. 1. 
-Generalized section of beds below the 
I'it tsburg coal. 
