56 J. J. STEVENSON — PENNSYLVANIA ANTHRACITE. 



(the northern termmation of the first bituminous basin), though con- 

 taining anthracite coals, has dips varying from 3 to 5 feet per hundred.* 

 But, as will be shown later on, this increase in complexity bears no 

 relation whatever to the character of the coal in the several anthracite 

 fields. 



Neglect of Conditions observable in the individual Basins. — A notable 

 source of error in the discussion lay in neglect of the conditions observ- 

 able along the trend in the several basins. From Pittsburg east-south- 

 east to Frostburg, in the Cumberland basin, one finds the conditions 

 already noted, with.greatty increased disturbance beyond that basin. 

 But let it be remembered that the extent of disturbance diminishes north- 

 ward in all the basins ; that the folding in and around the Middle and 

 Northern anthracite fields is less than that in and around the Broad 

 Top of southern Pennsylvania and the Cumberland in Maryland ; that 

 the flexures in the Loyalsock are less pronounced than those in Somerset 

 county of Pennsylvania, in the southern portion of the same first bitu- 

 minous basin. 



Discontinuity of Rogers'' s Line connecting anthracite and bituminous Ba- 

 sins. — A still more serious error was that of extending this single line 

 beyond the Cumberland basin across the anthracite fields. The line 

 from Pittsburg to Frostburg or to the Broad Top field is not continuous 

 -with that across the anthracite fields ; its eastern portion is j^arallel to 

 the latter line, and is equivalent to the line passing through the Northern 

 and Middle fields. There is no certainty in the impression that .if the 

 line were continued beyond the Broad Top field or the Cumberland 

 basin anthracite conditions would be reached.f As has been stated on a 

 former page, the Broad Top coal-field may be taken fairly as represent- 

 ing the Northern field. 



True Statement of Relation of Disturbance to Amount of Volatile. — The true 

 statement is that the decrease in volatile combustible matter, as shown in 

 the easterly basins, is not merely toward the east, but also and more nota- 

 bly toward the north, along the trend, and apparently without any rela- 

 tion whatever to the degree of the disturbance ; for in the former case 

 the decrease is in the general direction of increase of disturbance ; in the 

 latter, the decrease is in the general direction of decrease of disturbance. 

 Not to multiply details here, as they will be needed in another part of 

 this discussion, it suffices to emphasize two facts : The driest anthracite 

 is not found in the Southern anthracite field, which contains the most 



* Ashbui-ner : Ann. Rep. Second ^Teol. Survey Penn. for 1885, pp. 283-284. 



fThis statement is made cautiously, for in northern Virginia the Poeono coals, lying in a line 

 with the Southern anthracite field, sometimes approach anthracite, but the ratios show extreme 

 variations. 



