LIMESTONE. 
121 
following analyses. In Washington County the limestone was con- 
siderably used in early days in the manufacture of natural cement, 
but is nowhere suitable for Portland cement, on account of the large 
proportion of magnesia. 
Analyses of Benwood limestone from Washington County. 
Insoluble res'due 
Calcium carbonate (CaC0 3 ) . . . 
Magnesium carbonate (MgC03) 
Ferrous carbonate (FeC0 3 ) 
Alumina (AI2O3) 
Sulpbur 
Phosphorus 
1. 
2. 
3. 
13.300 
22. 520 
15. 750 
68. 837 
48. 823 
47.080 
14. 649 
20.621 
28. 528 
3.306 
f 3.625 
i 3.523 
7.511 
.097 
.203 
.069 
.049 
.051 
.127 
100. 238 
99. 366 
99. 065 
14.920 
47. 750 
30. 943 
5.608 
.126 
.015 
99. 362 
1. One mile north of Canonsburg; upper layer, very hard and compact, like conglomerate, bluish gray 
Second Geol. Survey Pennsylvania, Rept. K, 1876, p. 388; analysis by A. S. McCreath. 
2. One mile north of Canonsburg; middle layer, compact, somewhat shal> bluish gray. Loc. cit.; 
analysis by D. McCreath. 
3. One mile north of Canonsburg; lower layer, hard, compact, unctuous, pearl gray. Loc. cit.; anal- 
ysis by D. McCreath. 
4. Property of Doctor Shaner, in Somerset Township, 8 miles from Washington. Second Geol. 
Survey Pennsylvania. Rept. MM, 1879, p. 285; analysis by I). McCreath. 
WAYNESBURG LIMESTONE. 
The Waynesburg limestone is a bed 4 to 20 feet in thickness, occur- 
ring below and within 40 feet of the Waynesburg coal. It is exposed 
and readily accessible at a number of places in various parts of the 
quadrangle. It is usually of a dark-gray color and makes a strong, 
but rather dark lime. The utility of this limestone has not been 
tested. 
LIMESTONES ABOVE THE WAYNESBURG COAL ( IN THE DUNKARD 
GROUP. 
Scattered throughout the Dunkard group are abundant limestone 
beds, which were described by the Second Geological Survey and 
given numbers from I to XIV, inclusive/' Several of these beds are 
known to be persistent over considerable areas and can be recognized 
as distinct beds. Most of them, however, in the upper portion of the 
Dunkard have been shown by recent field work in western Greene 
County to be local in their occurrence and many of them can not be 
correlated with any bed at a distance. The more important beds are 
described in the following paragraphs. 
LOCAL LIMESTONES BETWEEN THE WAYNESBURG AND WASHINGTON COALS. 
Below the Waynesburg U A" coal and above the Waynesburg 
sandstone there occurs locally a limestone which was noted by Stev- 
a White, I. C, Bull. U. S. Geol. Survey No. 65, 1891, p. 39. 
