80 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



by an interval of 12 to 30 feet ; the lower bed is the less persistent and is 

 very close to the Homewood sandstone. If the overlying sandstone be the 

 Clarion, it becomes necessary to regard these beds as representing the 

 Brookville, which in much of the bituminous area is a complex bed, while 

 farther southwest it occasionally divides in this manner; but the distance 

 of this region from any other where the relations are distinct makes posi- 

 tive correlation impossible.* 



FIRST BITUMINOUS COAL BASIN OF PENNSYLVANIA 



This, extending from the Alleghany mountains westward to Laurel Hill, 

 is traceable readily from Bradford county at the northeast across Lycom- 

 ing, Clinton, Center, Clearfield, Cambria, and Somerset counties of Penn- 

 sylvania into Garrett of Maryland and Preston of West Virginia. It is 

 divided in Pennsylvania by two anticlines, that at the west originating at 

 the northern extremity and the other in southeast Cambria, so that the 

 basin, double at the north, becomes triple in Somerset. The axes in- 

 crease southwardly in Pennsylvania, Laurel becoming a bold mountain, 

 the westerly fold growing into the great Viaduct axis and the Cambria 

 fold developing into Negro mountain. The interior folds approach each 

 other toward the Maryland line, so that the synclinal is too shallow to 

 hold the Coal Measures in Maryland. The easterly, or Salisbury, sub- 

 basin of Somerset becomes shallow in Maryland and the Allegheny beds 

 shoot out within 15 miles; but the western, or Johnstown, subbasin con- 

 tinues across Garrett into Preston of West Virginia, where, owing to the 

 lessening strength of the Laurel anticlinal, the Allegheny beds become 

 continuous with those of the Second Pennsylvania basin. 



The somewhat widely separated patches of coal-bearing rocks within 

 Bradford and Lycoming counties are confined to the western side of the 

 basin. The Barclay area of Bradford county shows four coal beds in a 

 vertical section of about 150 feet, which have been described by Mr Piatt. 

 How much of the section belongs to the Allegheny can not be determined.! 



The Lycoming areas known as Mclntyre and Pine creek are larger, and 

 Mr Piatt has measured the section there in detail as follows : 



* I. C. White : U. S. Geol. Survey Bull. no. 65, pp. 126-127 ; Geol. W. Va., vol. ii, 

 p. 354. 



C. C. O'Harra : Maryland Survey, Allegany county, p. 117. 

 G. C. Martin : The same, Garrett county, pp. 112, 115. 



W. B. Clark et al. : The same, vol. v, pp. 298-299, 300, 333, 335-341. Advantage has 

 been taken of delay in publication to insert here, as well as in the proper place under 

 Conemaugh, additional material contained in volume v of the Maryland Survey, which 

 has appeared since this manuscript was offered to the Society. 

 -f-F. Piatt: Bradford and Tioga (G), pp. 125-127. 



