78 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



blance in structure. The interval from the Barnett to the Cook coal bed 

 is commonly about 50 feet ; on the east side, in Huntingdon, it decreases 

 to 35 feet, but midway in the field within Bedford a shaft shows it but 8 

 feet. A thick bed of fireclay underlies the Barnett and another overlies 

 the Cook. In Bedford county the Cook coal bed varies from mere black 

 shale to 7 feet of coal within a few rods ; the quality of coal is inferior 

 and the bed is not worked ; but in Huntingdon county it has been worked, 

 for the coal is thicker and better. It usually shows three or four benches 

 separated by ordinarily thin partings, but one of these varies from 2 to 25 

 feet. On the east side of the field in this county the bed has its coals dis- 

 tributed through a vertical section of almost 48 feet.* 



The Georges Creek, or Potomac, basin, originating in Bedford and 

 Somerset counties of Pennsylvania, extends southward across Allegheny 

 and Garrett counties of Maryland into Mineral and Tucker counties of 

 West Virginia. Many measurements have been made by Messrs White, 

 Martin, and O'Harra, from which five may be selected, which are as fol- 

 lows, arranged from north to south: 



I II III IV V 



Feet. Inches. Feet. Inches. Feet. Inches. Feet. Inches. Feet 



Upper Freeport 5 4 2 5 4 5 2 8 



Interval 20 60 0~\ 



Lower Freeport 2 1 2 1 137 135 95 



Interval 74 55 ) 



Upper Kittanning 7 10 3 2 



Interval 65 45 42 61 40 



Middle and Lower Kit- 

 tanning 5 6 6 5 6 4 8 5 11 



Interval -\ C 85 80 121 65 



Clarion I 129 ) 2 6 2 4 1 6 3 



Interval ) (45 35 18 40 



to the Pottsville. 



I. Piedmont, West Virginia (I. C. White). 

 II. Above Harrison, Mineral county (I. C. White). 



III. Harrison, Garrett county, Maryland (G. C. Martin). 



IV. Henry, Garrett county, Maryland (G. C. Martin). 



V. Thomas, Tucker county, West Virginia (I. C. White). 



A full series of records published in 1906 shows that the Allegheny in 

 this area varies from 260 to 350 feet, the thickness being greatest in the 

 southern and eastern portions. The Upper Freeport coal bed, known 

 locally as the Thomas, is persistent throughout, but increases in thickness 



* J. J. Stevenson: Bedford and Fulton counties (T 2), pp. 62, 64. 

 I. C. White: Huntingdon county (T 3), pp. 52, 54, 55, 58, 59, 61, 66, 68. 



