DETAILED STRUCTURE. 39 
r angle, cast of the Amity, was surveyed in 1901 there was some 
doubt whether the anticline crossing Monongahela River near Belle- 
vernon was continuous with the one passing near Waynesburg, 
named by Stevenson. On account of this uncertainty and the fact 
that the term Waynesburg had been applied to two structural fea- 
tures this axis in the Brownsville quadrangle was named by M. R. 
Campbell a the Bellevernon anticline, and this name was continued 
by R. W. Stone in the Waynesburg quadrangle 5 surveyed a year 
later. 
The anticline crosses the southeast corner of the Amity quad- 
rangle and only about 1^ miles of the axis lies in this territory. The 
elevation of the Pittsburg coal on its crest is 800 to 840 feet. 
WAYNESBURG (PIGEON CREEK) SYNCLINE. 
This feature consists of a broad structural trough 10 miles wide 
lying between the Bellevernon anticline on the east and the Amity 
anticline on the west. It was named the Waynesburg syncline by 
Stevenson, but on account of doubt as to its continuity with the 
syncline having the same relations in the Brownsville quadrangle 
it was termed by Campbell c the Pigeon Creek syncline, after Pigeon 
Creek, in this county. The present survey demonstrated that the 
two synclines are one and the same, and since the name Waynesburg 
had priority the term Pigeon Creek was discarded in its favor. 
This syncline is a broad structural basin with generally low dips. 
The axis enters the quadrangle at Bentleyville and takes a slightly 
meandering course, averaging about S. 40° W., to the southern edge 
of the quadrangle. From Bentleyville it follows the valley of Pigeon 
Creek to Three and Four, where it turns southward and passes half a 
mile east of Scenery Hill, crossing West Bethlehem Township, and 
leaves the quadrangle directly south of Bissell. 
At the point where the axis of the trough enters the quadrangle 
from the east the Pittsburg coal is at an elevation of about 750 feet. 
From this point it descends gradually to the southwest until at "the 
Greene County line the coal is less than 400 feet above sea level. 
Throughout the basin the average dip is less than 100 feet per mile, 
except on the eastern side of the axis, between Zollarsville and Bealls- 
ville, where for short distances it is as much as 150 feet per mile. In 
this section the structure is largely determined from well records, 
and shows several rather peculiar nose-like projections from the flank 
of the anticline. These are presumably about as represented, as the 
well records seem to be mostly good, but in all cases due allowance 
should be made for the possibility of errors in the records. In the 
a Geologic Atlas U. S., folio 94, U. S. Geol. Survey, 1903. 
bldem, folio 121, 1905. 
cOp. cit. 
