28 ECONOMIC GEOLOGY OF AMITY QUADRANGLE, PA. 
ROCKS BETWEEN THE GREENBRIER LIMESTONE AND THE CATSKILL RED BEDS (POCONO 
FORMATION). 
General statement — The Pocono is the lowest formation in the Car- 
boniferous system. Its uppermost member, which corresponds with 
the Big Injun sand of the drillers (Burgoon sandstone of the Alle- 
gheny Front), extends downward 300 to 900 feet, according to differ- 
ent authorities. Considerable doubt exists as to the true position of 
its base, as there is a strong resemblance between the rocks contained 
in it and those of the Chemung formation at the top of the Devonian, 
and even where they outcrop it is difficult to draw a definite line of 
separation between them. Such a boundary can be accurately defined 
only on the evidence of fossils, and in a region where the only infor- 
mation comes from well sections no fossils are known. The weight of 
evidence in regard to the position of this boundary seems to be in 
favor of the lowest limit (over 800 feet), and in this report it is drawn 
provisionally at the top of a group of red shales just below the base of 
the Fifty-foot sand. a 
Character and thickness. — If the boundary as just defined is correct, 
the average thickness of the Pocono formation in the wells where its 
red-shale base can be determined is 875 feet. One of the best sections 
of the formation is that of the J. L. Thompson No. 4 well (47), given 
below : 
Section of Pocono formation in the J. L. Thompson No. 4. well, borough of Deemston 
Feet 
Sand, Big Injun 60 
Break 12 
Sand, Big Injun, bottom portion 200 
Slate 40 
Sand, Squaw 130 
Slat.- and shells 130 
Sand, Thirty-foot 60 
Red rock (Bedford?) 10 
Slate and shells .50 
Sand. Gantz 20 
Slate 20 
Fifty-foot sand 25 
Slate and shells 15 
Sand 20 
Slate and sand shells 40 
Sand 10 
Slate and shells 20 
862 
Directly below the bottom of this section is 10 feet of red rock, which 
is considered the top of the Devonian system. The Thompson section 
is fairly typical, but for comparison a second section, that of the Luse 
well (15) near Beallsville, is given. 
a For a discussion of the evidence on the position of this boundary, see the Amity folio (No. 144), 
Geologic Atlas U. S. 
