90 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



uncertain occurrence and the Johnstown cement extends northward to but 

 a little way beyond Clearfield.* 



Mr dTnvilliers reports several sections in northwestern Cambria show- 

 ing the varying intervals within an area of 8 or 9 square miles, thus : 



Feet. Inches. Feet. Inches 



Upper Freeport 3 6 to 4 



Interval 33 to 50 



Lower Freeport 3 to 4 6 



Interval 35 to 46 



Upper Kittanning 3 to 7 



Interval 34 to 49 



Middle Kittanning 2 to 2 



Interval 35 to 45 



Lower Kittanning 4 to 7 5 



Interval 15 to 22 .0 



Clarion 1 8 to 1 10 



Interval 30 to 30 



Brookville 2 to 3 



But while the intermediate intervals show such variation, that between 

 the Upper Freeport and Lower Kittanning varies only from 163 to 168 

 feet, the increase being southwestwardly, which continues, for on Black 

 lick the interval is 183 feet. The increase here is in the upper part of 

 the section between the Freeport coal beds. Shales predominate in all 

 of the sections, but the Freeport sandstone is present in two of them. 

 The Upper Freeport and Johnstown cement limestones are present in sev- 

 eral of the sections, especially on Black lick, where the Lower Kittanning 

 is the important coal bed.f 



In Indiana county the Second basin is known as the Ligonier valley, 

 and this name is retained southward into West Virginia. Most of the 

 area is covered by the Conemaugh, and the Allegheny is reached near the 

 mountains. Near the Clearfield line the Upper Freeport is 8 feet 4 inches 

 thick, carries on top 8 inches of bony coal, and is divided by a 4-inch 

 parting, thus resembling the structure observed at many places in the 

 First basin as well as farther north in this. A section on the west side 

 not far from the Clearfield line is: 



* Geology of Pennsylvania : Vol. ii, p. 525. 



E. V. d'Invilliers : (T 4), p. 124. 



H. M. Chance: (H. 7), pp. 38, 41-42, 46, 53, 55, 61, 93, 96, 99, 103, 116, 129. 



I. C. White: Bulletin no. 65, p. 123. 

 t E. V. d'Invilliers : Final Report, plates 415, 418, opposite pp. 2222, 2230. 



