Stratigraphy — Continued. , Page. 
Rocks which do not outcrop — Continued. 
Carboniferous system — Continued. 
Pennsylvanian series — Continued. 
Pottsville sandstone or Salt sand (Pottsville formation) 
Definition 
Character and thickness 
Mississippian series 
Rocks between the Pottsville (Salt sand) and Burgoon (Big 
Injun) sandstones ( Mauch Chunk formation) 
Definition 
Character and thickness 
Unconformity 
Greenbrier limestone ( Big lime ) 
Rocks between the Greenbrier limestone and the Catskill 
red beds ( Pocono formation ) 
General statement 
Character and thickness 
Red shale (Bedford?) 
Devonian system 
Rocks below the top of the Catskill red beds (Chemung for- 
mation ) 
General character 
Catskill (or sub-Blairsville) beds 
Sandstones 
Beds lower than those penetrated in the Amity quadrangle.. 
Geologic structure 
Method of mapping 
Structure contours 
Degree of accuracy s 
Limits of error 
Structure in detail 
Structure of Pittsburg coal 
Bellevernon anticline 
Waynesburg (Pigeon Creek) syncline 
Amity anticline 
Nineveh syncline 4] 
Washington anticline 41 
Relation of structure of Pittsburg coal to structure of other beds 45 
Lack of parallelism between beds 4$ 
Structure of Gantz sand 45 
Mineral resources 45 
Petroleum and natural gas 45 ■ ; 
Distribution of oil and gas fields in the Amity quadrangle 4$ 
Brief history of development in Washington County 44 
Early history 4- 
Washington field 4£ 
Fonner field 41 
Zollarsville field 4* 
Oil and gas rocks 4i 
Description of the map 41 
Depth of wells 4J- 
Mode of occurrence of oil and gas 4£ 
Oil and gas sands 4£ 
