12 ECONOMIC GEOLOGV <^V AMITY QUADRANGLE, PA, 
burg coal up to the uppermost beds in the Appalachian basin. The 
rocks were formerly known as the Upper Barren Measures, for the 
reason that with rare exceptions they do not carry workable coal beds, 
and they lie higher up in the strata than the Lower Barron Measures. 
Character and thickness. In the Amity quadrangle the greatest 
thickness oi the Dunkard beds is about 750 feet, in Morris Township, 
Greene County, in the extreme southwest corner oi the quadrangle. 
The hods of this group dip tow ard the southwest and reach their maxi- 
mum depth below the surface somewhere in the vicinity oi the head- 
waters of Dunkard Creek, near the boundary between Pennsylvania 
and West Virginia, In that region some oi the hills reach altitudes of 
over 1,100 feet above the base oi the group. 
These rocks vary greatly in different regions. In general they con- 
sist oi shales and shah sandstones, but a few more or less persistent 
beds of rather massive sandstone are known, and in the lower portion 
of the group there are several important limestones. This portion 
also contains a number of coals, but they are usually oi Little economic 
value. In Greene County the Dunkard group carries many beds oi 
red shale. These increase in importance toward the southwest and 
are most prominent in West Virginia, but toward Washington County 
they disappear, giving way entirely to the ordinary drab or yellowish 
shales, traces oi which can be seen in some of the highest hills in the 
southwestern part oi the quadrangle. 
Division of the group. — The Dunkard group was formerly considered 
a formation, like the Conemaugh and Monongahela, but in this area 
the lower portion is much more calcareous than theupper portion, and 
contains several minor coal beds; it is therefore considered as a dis- 
tinct formation. The line oi division is the top oi the Upper Wash- 
ington limestone, the most persistent and most easily recognizable 
member of the group. The Dunkard beds above this line are known 
as the Greene formation and those below as the Washington forma- 
tion, from the respective counties in which they are typically devel- 
oped. 
ROCK- aRcvk niK UPPER WASHINGTON UMBSTONl WE FORMATION 
Character. — In eastern Washington County no good section of the 
Greene formation has been measured. Tn his report on the Greene 
and Washington district Stevenson 7 gives the following section for 
Center Township, Greene County, which is of value to show the gen- 
eral nature of the rocks, though there is a wide variation in their inter- 
vals and character: 
nd Geol. Survey Fennsylvan . . I , p. 35. 
