70 J. J. STEVENSON— CARBONIFEROUS OF APPALACHIAN BASIN 



not observed elsewhere. The Mercer coals are shown in the eastern part 

 wherever their place has not been taken by the sandstone. The extreme 

 thickness of Mercer is 122 feet, and the limestones are wanting. The 

 Connoquenessing sandstones are exposed on the Armstrong border, where 

 they are each 20 feet, separated by 43 feet of Quakertown shales, showing- 

 no coal.* 



Armstrong county is south from Clarion, between Butler at the west 

 and Indiana at the east. On the northern border, along Red Bank creek, 

 the section is 



Feet 



Homewood f .• 50 to 75 



Mercer 40 



Connoquenessing 150 



Sharon shale 13 



Sharon sandstone 50 



The Mercer coal beds are represented by a 2-inch streak in the upper 

 portion, but there is no trace of the Mercer limestones. The Connoque- 

 nessing is a continuous mass of sandstone along the boundary between 

 Clarion and Armstrong for several miles, and, like the Sharon sandstone 

 below, appears to be without pebbles. Farther northwest, on the Butler 

 county border, the condition is the same, for 115 feet of Connoquenessing 

 was seen above the river; but both of the Mercer coal beds are present 

 there, as they are also at another locality 8 or 9 miles southwest. 



In the northern half of the county, east from the Allegheny river, the 

 Homewood sandstone is shown at several localities along that river, dis- 

 appearing finally under the stream at about 5 miles above Kittanning. 

 An interesting section is shown on Mahoning creek within 3 or 4 miles 

 of the Indiana line. It is given here in detail : 



Feet. Feet 



Homewood sandstone 40 



Concealed 12 



Mercer group 96 



Black shale 10 . / 



Sandstone 10 



Shale.. 17 



Limestone 6 



Concealed 50 



Shales and ore . . 13 



Upper Connoquenessing 42 



Quakertown shales, sandy, seen 10 



* H. M. Chance : Northern Townships of Butler County (V), 1879, pp. 42, 70, 96, 102, 118, 122, 132. 



t Here, as in several other sections, the writer has applied the now accepted names to parts of 

 the section, though they were not used by the authors of reports from which the records are 

 taken. For discussion of the relation, here accepted, see under "Correlation" in a later portion 

 of this paper. 



