PENNSYLVANIA^ SERIES. 17 
A section was once exposed in a shaft sunk to the Pittsburg coal 
opposite the Chestnut street station, in Washington. a The upper 29 
feet 6 inches of this belongs to the Washington formation, and the 
8-inch coal is the Waynesburg seam. 
Section in old shaft, Washington. 
Ft. in. 
Washington formation 29 6 
Monongahcla formation: 
Coal {Waynesburg) 8 
Shale, gra}^ 6 
Sandstone 5 
Limestone and shale (Benwood limestone), etc 170 
Slate, black 12 
Limestone, gray (Fishpot) 13 
Shale, blue 50 
Sandstone (Pittsburg) 15 
Shale ." 3 
Coal, Pittsburg 5 6 
280 8 
About 1J miles north of Washington is the old Enterprise shaft, 
sunk to the Pittsburg coal many years ago. b Tnis gives only a partial 
section of the formation, as the remaining rocks lie above the surface. 
Partial section of Mo nongahela formation in Enterprise shaft, 1\ ndles north of Washington. 
Ft. in. Ft. in. 
Soil 4 
Limestone 45 
Coal, Sewickley 4 
Limestone 30 
Shale 45 
Coal, Redstone 3 
Sandstone 20 
Shale 1 
Coal, Pittsburg: 
Roof division . 2 . 
Clay 1 | 8 10 
Lower division 5 10 ' 
The principal evidence of the thickness of the formation is from a 
number of oil and gas wells which record both the Waynesburg and 
Pittsburg coals. Although it is necessary to make an allowance of 
a few feet for inaccuracies of measurement, these indicate that the 
formation is not at all uniform in thickness. The following is a list 
of wells giving the measurements between the top of the Waynes- 
burg and the bottom of the Pittsburg coal in various parts of the 
quadrangle. 
a Stevenson, J. J., Second Geol. Survey Pennsylvania, Rept. K, 1876, p. 248. 
b Stevenson, J J., op. cit., p. 240. 
Bull. 300—07 2 
