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. 



Nim ish ilk ; i Valley . 



Hoivenstein. 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 fotmd 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 ijOO 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 l-l 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 



