PENNSYLVAN1AN SERIES. 
15 
Distribution. — The rocks of this formation cover a larger area in 
this quadrangle than those of any other. They occupy the surface of 
nearly all the central portion, the exceptions being patches of the 
Greene formation which cap the hills along the Waynesburg and 
Nineveh synclines. The formation also outcrops along the main 
branches of Tenmile Creek and up its tributary valleys on the north. 
On the eastern and northern borders of the quadrangle it forms the 
hilltops and crests of the ridges above the Monongahela formation. 
PENNSYLVANIAN SERIES. 
ROCKS BETWEEN THE TOP OF THE WAYNESBURG COAL AND THE BOTTOM OF THE PITTSBURG 
COAL (MONONGAHELA FORMATION). 
Definition. — The Monongahela formation extends downward from 
the top of the Waynesburg coal to the bottom of the Pittsburg coal, 
and in this quadrangle varies from 280 to 360 feet in thickness. In 
the reports of the Second Geological Survey of Pennsylvania it is 
known as the Upper Productive Measures, to distinguish it from a 
similar productive formation much lower in the series. 
Character and thickness. — The formation consists predominantly of 
limestones, but also contains shales, occasional sandstones, and at 
least three valuable beds of coal. The best recorded section in Wash- 
ington County was measured by I. C. White/ near West Brownsville, 
and is as follows : 
Section of Monongahela formation near West Brownsville. 
Ft. in. Ft. in. 
Coal, Waynesburg: 
Goal . 10 1 
Clay Z\ 3 7 
Goal 2 6' 1 
Shale and sandstone 45 
Shale, bituminous, Little Waynesburg coal 1 6 
Limestone, Waynesburg 10 
Sandstone, shaly 40 
Coal, Uniontown 3 
Shale and sandstone 28 
Limestone, with thin shale 88 
Goal, Sewickley Blossom. 
Sandstone, shaly 32 
Limestone 30 
Shale 20 
Coal, Redstone 1 
Sandstone and shale 45 
Coal, Pittsburg, roof- 
Coal g\ 
Clay 3 
Coal 1 \ 2 6 
Clay 1 | 
Coal, Pittsburg, main bench 7 
368 
a Bull. U. S. Geol. Survey No. 65, 1891, p. 45. 
