656 HISTORICAL GEOLOGY. 



improbable that it was a prominent source, since tlie same process which 

 will convert vegetable tissues into coal or mineral uil (page 124), will pro- 

 duce a like result from animal oils. 



Equivalent coal-beds in the series. — Since the coal marsh area of Pennsyl- 

 vania, eastern Ohio, Kentucky, and West Virginia was in all probability 

 essentially continuous, it is reasonable to look for the beds over the areas 

 that are of equivalent age. It has been found difficult, however, to make out 

 even the relations between those of eastern and western Pennsylvania; that 

 is, of the Anthracite and Pittsburg regions. The related West Pennsylvania 

 and Ohio beds are more easily correlated. But any parallelism between the 

 beds of Pennsylvania and those of Illinois and other states of the Mississippi 

 valley, unless in the Lower Coal-measures, is improbable. 



Coal-measures. — Full details with regard to the Bituminous Coal-measures of western 

 Pennsylvania, West Virginia, and partly of Ohio, will be found in a Report by I. C. 

 "White, constituting Bulletin 65 of the U. S. Geological Survey. The following are facts 

 from eastern Pennsylvania : — 



In the Panther Creek basin at Tamaqua, where the total thickness is 2168', the lowest 

 coal-bed is the Lykens Valley coal, 6' thick, within the Pottsville conglomerate. 240' above 

 is the A coal-bed, 16'; 115' higher, the B coal-bed, 9'; 235' higher the C coal-bed, 8' (with 

 a thin bed between) ; and then, 122' above the last, the Mammoth bed, including beds D, 

 12', and E, 24', and another between of 5', together with 45' and 48' of intervening rock. 

 211' higher comes the F, or Lower Red Ash coal-bed, 10'; 56' higher, the Bony coal-bed, 

 4'; 46' higher, the G, or Uj^per Bed Ash coal-bed, 6'; 84' higher, the Washington coal-bed, 

 3'; 92' higher, the Jock coal-bed, 7'; and then 4 coal-beds of 2' each in the next 150'; 158' 

 higher, the First Upper Bed Ash coal-bed, 4'; 106' higher, the Second Upper Bed Ash 

 coal-bed, 3'; 63' higher, the Third Upper Bed Ash coal-bed, 1'. From the Mammoth to 

 the Lykens valley coal-bed the coals are of the White Ash group ; the remainder are 

 divided into the Upper and Lower Red Ash groups, along a plane below the third coal-bed 

 from the top. 



In the Pottsville basin, between the Mammoth and Lykens Valley coal-beds, there are 

 7 coal-beds ; and one, 660' above the Lykens, called the Buck Mountain coal-bed, is 8' 

 thick. The Wilkesbarre section gives widely different results. In western Pennsylvania 

 the Coal-measures have their greatest thickness at the West Virginia line, midway in 

 Greene County, Pa. ; and from this point there is a thinning westward to about one third. 

 Passing into Ohio, the interval between the Pittsburg and Uniontown coal decreases north- 

 ward from 200' to 60' or less (Stevenson). 



The Pottsville conglomerate in Mercer County, Pa., afforded I. C. White (Fa. Bep. 

 Q, 3, 1880) the following section : — 



Homewood sandstone 50', shales 5', iron ore 2', limestone 21' 59|' 



Coal, Upper Mercer , 2i' 



Shales 25', iron ore 2', Lower limestone 2^', shales 10' 39i' 



Coal, Lower Mercer 2^' 



Shale 10', iron ore 1', shales with Upper Connoquenessing sandstone.. 66' 



Coal, Quakertown 2' 



Shales, Lower Connoquenessing sandstone 30', Sharon shales 30' 100' 



Coal, Sha7'on 4' 



Fire clay and shale 5', Sharon conglomerate 20' 25' 



The thickness of the Coal-measures in Ohio is about 1250': the Lower Productive 250', 

 with 7 coal-beds ; the Lower Barren, having the Mahoning sandstone at its base, 500'; 



