Mar., 1910.] 
Pennsylvanian Limestones. 
95 
United States Geological Survey, from railroad elevations, and 
in a few cases from topographical maps. In every case the 
elevation given below will be understood to mean the elevation of 
the top of the stratum named, and intervals between strata will 
be understood to mean between their tops unless otherwise 
explained. 
Other strata associated with the limestones receive attention 
only in so far as they add interest to the setting and identity of 
the limestones in different places, or when well-known horizons 
are exhibited and call for brief recognition. 
DESCRIPTION OF SECTIONS. 
Nimishillen Valley. 
Howenstein. In the valley of the Nimishillen about six miles 
south of Canton and about four miles north from the county 
line good outcrops of limestones are found near the village of 
Howenstein. A rather long section is afforded here since the 
valley is narrow and deep and the hills rather high. Almost 
every foot of the strata may be seen from the Lower Mercer Lime- 
stone in the bed of the stream up to thirty feet or more above 
the Middle Kittanning Coal. At Howenstein a limestone is 
found in the creek bed but cannot be seen well here. At Mr. 
John Shew’s Mill a half mile below the village the limestone is 
still found in the stream bed. 
A wall under the mill is constructed of this stratum lifted from 
the stream bed and the thickness is seen to be 10 to 12 inches. 
It is reported by Mr. Shew to be one foot or a little over and lifts 
in two layers. It is underlain by a thin coal and is dark gray 
in color weathering to a yellowish gray. Segments of crinoid 
stems and brachiopods constitute the fossils seen. The lime- 
stone can be seen some distance below the mill in the creek bed. 
Above the railroad on the west side of the stream occurs a 
second limestone which is undoubtedly the Upper Mercer as will 
appear from sections to follow. This point is about 300 yards 
below the mill, and the interval from top to top where measured 
is 28 feet which is greater than the usual interval between these 
limestones. The interval is usually 20 to 25 feet. At this out- 
crop the Upper Mercer is 14 inches thick and in one layer. In 
other characters it is practically like the lower limestone. Four 
hundred yards above the mill and on the west side of the railroad 
this stratum is seen to be 21 inches thick and resting upon 18 
inches of coal. It is also seen to rise and fall, or undulate and is 
certainly considerably less than 28 feet above the lower limestone, 
probably less than 20 feet in places. It can be seen at a number 
of points along the railroad up to Howenstein where it is seen at 
several points on the east side of the creek in the bank above 
