OBJECTIONS TO ROGERS's HYPOTHESIS. 55 



Erroneous Conclusions as to Relation of Disturbance to Amount of Volatile. — 

 The first serious error in Professor Rogers's discussion is in reference to 

 the relation of increase in dip to decrease in volatile combustible matter. 

 He believed that the increase in rate of dip is steady and marked along a 

 west-northwest and east-southeast line. True, the dip does increase from 

 Pittsburg along that line to the Cumberland (Potomac) basin in Mary- 

 land ; and the increase is remarkable if one compare the extremities of 

 the line ; but the increase is not regular. As was stated on a previous 

 page, the increase is moderately great from Pittsburg to the foot of Chest- 

 nut ridge in the Councils ville basin, from 1° at Pittsburg to 10° on the 

 side of Chestnut ridge; but there is no further increase until be^^ond the 

 Alleghany mountain, for in that monoclinal one rarely finds a dip of 

 more than 10° near the line under consideration; but immediately be- 

 yond the Alleghany one comes to great folds, with dips of from 20° to 

 50°, sometimes Avith inversions. The dip on the easterly side of the 

 Cumberland basin (the Mount Savage synclinal) within Bedford count}'' 

 of Pennsylvania is sometimes more than 80°.^^ 



Along the line chosen by Professor Rogers the Pittsburg coal-bed shows 

 the following variations, the results being the average of analyses in each 

 basin and the calculations being made without reference to water and 

 ash : Pittsburg, 40.7 ; in the next trough eastward, 39.2 ; in the Greens- 

 burg, 35.3 ; in the Connellsville or Coke, 33.8 ; there the dip is from 4° 

 to 6° in the mines ; in the Ligonier valley, 28.1 ; in the Salisbury basin 

 of Somerset county, 23.3 ; in the Cumberland basin of Mar3dand, 18.8. 

 The decrease in proportion of volatile matter is greater in passing from 

 Connellsville to Salisbury, about 34 miles along the dip, with no change 

 in type or extent of disturbance, than it is in passing from Pittsburg to 

 Connellsville, about 32 miles, with great change, or from Salisbury to 

 Frostburg, in the Cumberland basin, about 15 miles, with the extreme 

 change in extent and type of disturbance on both sides of the Cumber- 

 land basin. 



It is very true that, along a similarly east-southeast and west-northwest 

 line across the anthracite fields, a great increase of complexity is observed 

 toward the east. The area of greatest disturbance is in the Great valley 

 beyond the Southern anthracite field ; folding is much more marked 

 and the distortion is much greater in that field than in the others ; the 

 flexures become broader and gentler toward the northwest, so that in 

 the Northern anthracite field one finds a typical canoe basin, with only 

 moderate dips, while the Loyalsock or Bernice, still further northwest 



* Second Geol. Survey Penn. Rep. on Bedford and Fulton Counties, 1882, p. 104. For notes respect- 

 ing the conditions in West Virginia, see I. C. Wliite : Proc. Amer. Piiilos. Society, vol. xix, 1881, p. 438 

 et seq. 



Vril — Rar.r,. Gpor,. Soc. Am., Vor,. 5,1893 



