122 ECONOMIC GEOLOGY OF AMITY QUADRANGLE, PA. 
enson, but not named. It is well exposed on Dunkard Creek, at 
Mount Morris, Greene County, and has therefore been designated byi 
I. C. White a the " Mount Morris limestone." In places in Washing- 
ton County it is 5 to 10 feet thick, but is not persistent. It can be 
seen at many points in the eastern half of the quadrangle. It is com- 
monly blue gray in color and weathers yellowish. 
A limestone is often found above the Waynesburg "A" coal also. 
It reaches a thickness of 8 to 10 feet and has generally a buff color. 
By I. C. White it was named the "Colvins Run limestone," from 
Colvins Run, in Greene County. 
LIMESTONES ABOVE THE WASHINGTON COAL. 
LOWER WASHINGTON LIMESTONE. 
This is the lowest of the three principal limestones occurring near 
Washington and named after that town. It forms the roof of the 
Washington coal. 1 [ere and there, however, a few feet of shale inter- 
venes between the coal and the limestone. The Lower Washington 
occurs from 150 to 220 feet below the top of the Upper Washington 
limestone and 120 to 150 feet above the Waynesburg coal. Wash- 
ington County is the region of its best development, and here its 
thickness ranges up to 30 feet. It is generally interstratified with 
much shale, as shown in the following section: 
Section of Lower Washington limestone and associated shale on Smith Run. 
Ft. in. 
Limestone 9 6 
Shale, black 5 
Limestone 7 
Shale black 4 
Limestone - 1 
Shale, black and soft - 2 
Limestone 2 
Shale, black 2 
Limestone, ha id. blue to black, weathers white 9 
Shale, soft . black 2 
Fire clay shale, dark ' 4 
Coal, bony 2 
Shale, black 4 
Fire-clay shale, dark - 5 
15 5 
An illustration of the outcrop of the above section is given in PL 
VII, B. 
One mile southeast of Hackneys station, near Tenmile Creek, the 
following section was measured : 
a White, I. C., Bull. U. S. Geol. Survey No. 65, 1891, p. 39. 
