PART II.—DETAILED DESCRIPTIONS. 
CHAPTER I. 
GENE UAL ST RAT IGUAP1IY. 
INTRODUCTION. 
The second part of this bulletin is intended to include such detailed 
information as will assist in the further investigation of the area or 
of adjacent areas. For this purpose a description of the different 
members which make up the formations will be given, together with 
an account of their peculiarities and their positions relative to other 
members, all of which assist in the identification of the different 
marking strata. After this each quadrangle will be considered sepa¬ 
rately by townships, the topographic position of the outcrops of the 
principal beds that have been located being described. 
The rocks to be considered include a section of about 3,000 feet, 
extending from a horizon near the. base of the Devonian system 
nearly to the top of the Carboniferous. 
The sequence of the formations is shown by the following section: 
General geologic section in Steubenville, Burgettstown, and Clagsvillc 
quadrangles. 
Series. 
Formation. 
(Greene . 
Permian. 
Pennsylvanian... 
Mississippian. 
(Washington. 
(Monongahela, including Pittsburg coal. 
Conemaugh .*... 
Allegheny. 
Pottsville. 
Mauch Chunk. 
Greenbrier. 
Pocono . 
Catskill . 
System. 
Carboniferous. 
Devonian. 
Approximate 
thickness. 
Feet. 
a 500 
275 
325 
500 to 600 
250 to 350 
150 to 350(?) 
0 to 100 
0 to 125 
750 to 850 
* Greatest thickness. 
In the detailed description of the rocks they will be considered by 
formations, those from the base of the Monongahela formation 
in ascending order to the highest strata found in the area being first 
discussed, and then each stratum from the base of the Monongahela 
67 
