70 OIL AND gas; OHIO, WEST VIRGINIA, PENNSYLVANIA. 
and leaves the limestone ledges in bold relief. This limestone is the 
most persistent feature of this part of the Monongahela formation. 
The Dinsmore limestone is overlain by about 20 feet of shale, 
which is olive-green in color on top and red or yellow below. 
Bulger limestone .—Above the shale just mentioned is another char¬ 
acteristic layer of limestone, which is treated as a separate member 
of the Monongahela formation and is named from the town of Ilulger, 
Washington County, Pa. In the type locality it is prominent, form¬ 
ing terraces on the sides of the hills, and consists of a solid brown 
limestone from 1 to 2 feet in thickness, breaking with an uneven 
fracture and showing a number of small crystals of calcite. West 
of the type locality, in the Steubenville quadrangle, the Bulger lime¬ 
stone has a thickness of a foot or more, is of a muddy brown color, 
and breaks with a smooth fracture. Its stratigraphic position, how¬ 
ever, remains constant, and it is underlain by the same green shale. 
It makes a reliable key rock in most of this region. 
Top beds .—Usually four separate beds of limestone can be identi¬ 
fied above the Bulger limestone, though they are not well developed 
in the Steubenville quadrangle. Immediately overlying the Bulger 
limestone is 15 to 20 feet of coarse calcareous shale, above which is 
solid limestone about 1 foot thick. This rock shows a yellow surface 
when weathered and is blue when freshly broken. The Aveathered 
surface always shows small protuberances, due to the presence of 
particles that are more resistant than the surrounding matrix. This 
gives it the appearance of being covered with small pimples, and by 
this peculiar and characteristic feature it may be easily recognized. 
Ten feet above this limestone is another about 1 foot thick, composed 
of two slightly different materials which on weathering give a spotted 
surface. This appearance is characteristic and seiwes to identify the 
rock wherever it is found. From 16 to 18 feet above the last-men¬ 
tioned bed is a blue limestone, which on weathering has a white resi¬ 
due of clay upon its surface, but despite this fact the rock is easily 
distinguished from the other white limestone, for the blue generally 
shows through the surface color. A foot or so above this bed is the 
top stratum of the Benwood limestone. On a weathered outcrop this 
is a soft yellow limestone, but on fresh fracture it sIioavs a brownish - 
red color. It disintegrates readily and is seldom found in a solid 
ledge. Usually its outcrop is marked by the presence of brown lime¬ 
stone nodules. 
UNIONTOWN COAL. 
A feAv feet aboA T e the Benwood limestone is the Uniontown coal, 
which has little or no economic importance in these quadrangles. It 
is less than 1 foot thick, and its outcrop is in many places concealed 
