ORIGIN OF THE PENNSYLVANIA ANTHRACITE. 685 



of coal exclusive of slate and other partings, but those for the 

 Bituminous areas include the slates and other partings, so that 

 the actual amount of coal is less than the figures indicate. It is 

 sufficiently clear that the conditions favoring the* accumulation 

 of coal in beds continued longer without interruption in the 

 anthracite region than they did elsewhere within the Appalachian 

 basin ; for the contrast is equally marked, when the anthracite 

 region is compared with the Virginias or Kentucky further south- 

 westward. The process of conversion also continued longer 

 without interruption, as the chemical analyses show. 1 Thus, in 

 the Anthracite Strip, one finds : 



Cumberland Field (only the Pittsburgh), 4.47- 4.78 Coal, 13' 

 Broad Top Field, - - - 3.26-4.64 Coal, 14' 



Southern Anthracite Field, 



Southern prong, - - 4.36-12.40 Coal, 18 '-30' 



Main Field, - - - 11.64-23.27 Coal, 30 '-60' 



Western Middle Field, - 19.87-24 Coal, 40 '-58' 



Eastern Middle Field, - - 25.53-30.35 Coal, 52 '-53' 



Northern Field, - - 19.37-19.92 Coal, 44 '-53' 



The anthracite analyses are commercial, samples chosen from 

 carload lots. Very much higher ratios are obtained by sampling 

 single benches. 



The First and Second Bituminous basins show a similar 

 change along the line of trend, the amount of volatile decreasing 

 northwardly as one approaches the old shore line. 2 Thus, in the 

 First, the Clarion coal bed shows from 2.94 to 4.84 near the 

 Maryland line, but from 7.07 to 10.28 in Sullivan county, where 

 is its last exposure at the north. In the Second basin, the Upper 

 Freeport coal shows 2.26 to 2.85 near the Maryland border, but 

 3.96 to 4.48 at the last northerly exposure, in Lycoming county. 

 The variations in the Third and other basins are less, as one 



1 The figures here given are the ratios between the Fixed Carbon and the Volatile 

 Combustible, the ash and water being ignored ; the more volatile, the smaller the 

 ratio. 



2 Some curious variations, apparently contradictory of the statement here made, 

 occur in the analyses. These will be discussed and their interest shown by the writer 

 in a review of theories respecting the origin of coal beds, which is now in course of 

 preparation. 



