178 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



40 feet. At the next exposure, 7 or 8 miles west, the limestone already 

 referred to is at 50 to TO feet above the Upper Freeport, but no coal 

 appears above it. Still farther west the coal is shown on the hilltops at 

 65 feet, while at 5 miles beyond, in Columbiana county of Ohio, Doctor 

 White finds the interval 55 feet, with the massive conglomerate Buffalo 

 sandstone resting on it. 



Going southward along the Ohio line, one has this section at the Ohio 

 river : 



Feet 



1. Sandy shale 20 



2. Pine Creek [Cambridge limestone] 2 



3. Buffalo sandstone and sandy shale 65 



4. Brush Creek limestone 1 



5. Brush Creek coal and concealed 5 



6. Mahoning sandstone, massive 80 



to the Upper Freeport coal bed. At 3 miles east the massive Buffalo 



sandstone rests directly on the Brush Creek coal, which is 95 feet above 

 the Upper Freeport. There seems to be no escape from the conclusion 

 that the coal bed, 55 to 65 feet above the Upper Freeport in Lawrence 

 and 99 to 65 feet in Beaver, is the same bed and at the Brush Creek 

 horizon. If the limestone seen in central Beaver be the Mahoning of 

 the eastern counties, the Upper Mahoning interval disappears northward 

 and westward, bringing the Brush Creek coal down to the place of the 

 Gallitzin coal. 



A new coal horizon appears in eastern Beaver at 30 to 40 feet above 

 the Brush Creek coal, dividing the Buffalo sandstone. Its place is ex- 

 posed at only one locality.* 



Southward from the area thus far described the Monongahela soon be- 

 comes the surface formation, and, except where anticlines are cut by 

 streams, one finds only the upper portion of the Conemaugh exposed and 

 the records of oil borings are the chief source of information. The 

 thickness of the Conemaugh at the north is about 600 feet, but it de- 

 creases southward to about 560 feet at the West Virginia line. 



South from the Kiskiminitas and east from the Monongahela river 

 are eastern Allegheny, Westmoreland, and Fayette counties, the last ex- 

 tending to the West Virginia line. The Little Pittsburg coal beds, ap- 

 proximately 20 and 60 feet below the Pittsburg, are fairly persistent, 

 though never economically important. Three limestones, to 13, 45, 

 and 60 feet below the Pittsburg, are shown at many places, though one 

 rarely finds them all in a single section. The Clarksburg limestone 



* I. C. White: (Q), pp. 179, 180-181. 183, 187-189, 208, 213-214, 223, 226, 235, 240, 

 245, 257, 260, 263; (Q 2), pp. 276, 282. 



