56 J. J. STEVENSON — CARBONIFEROUS OF APPALACHIAN BASIN 



burg region at the northeastward and the Cambria at the south. Mr 

 Ashburner's section shows 



Feet. Inches 



1. Johnson's run sandstone 55 



2. Alton upper coal bed 4 



3. Alton shale and sandstone' 36 



4. Alton lower coal bed 3 2 



5. Kinzua sandstone 33 



6. Upper Marshburg coal bed 1 



7. Olean conglomerate Not measured. 



Very frequently another coal bed, the Alton middle, appears in sec- 

 tions of this and adjoining counties.* 



The section is one within Tioga, Potter, Lycoming, and Clinton, only 

 with variations in thickness or composition of the several members. It 

 is characteristic also of Cameron and Elk, the counties west from Clinton, 

 as well as of McKean, lying north from those counties along the New 

 York border. Thus in Cameron county Mr Ashburner rinds 



Feet. Inches 



1. Sandstone 27 



2. Coal and shale . 10 8 



3. Fireclay and shale , . 8 



4. Coal and shale 6 



5. Shale 19 



6. Sandstone 125 



Total 195 



The Connoquenessing (Kinzua) and Sharon (Olean) sandstones are 

 not distinguished in the section, but Mr Ashburner states that a coal 

 bed at times occurs almost midway in the lower sandstone. The section 

 is similar in Elk county, where the Alton coals are frequently thick 

 enough to be mined ; so also farther west, in the same county, within 

 Rogers fifth basin, where the total thickness is 182 feet. Sometimes a 

 lower bed, the Lower Marshburg coal bed, is found. The coal beds are 

 extremely irregular in their occurrence, and their variable thickness leads 

 Mr Ashburner to speak of them as lenticular. It may be well to give 

 Mr Ashburner's generalized section for McKean county : 



Feet 



1. Johnson Run sandstone 30 to 75 



2. A lion coal group 20 to 35 



3. Kinzua sandstone 45 to 60 



4. Marshburg upper coal and shale 5 to 15 



5. Olean conglomerate ... . 45 



*C, A. Ashburner (G 4), p. 74, 



