BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 5, pp. 39-70, PL. 2 November 22, i893 



ORIGIN OF THE PENNSYLVANIA ANTHRACITE 



BY JOHN J. STEVENSON 



{Read before the Society August 15^ 1893) 

 CONTENTS 



Page 



Introduction 40 



Pennsylvania Coal Areas 40 



General Extent 40 



Geoloofic Structure " 41 



Anthracite Strip 41 



Bituminous Basins 42 



Relation to Marj^land and Virginia Coal Areas 43 



Extent of Deformation of the several Coal Basins 43 



Anthracite of Arkansas 45 



Anthracite Field of Donetz, Russia 47 



V^ariation in the volatile Combustibles in Pennsj'lvania Coals 47 



Hypotheses as to Causes of A'ariation 48 



Rogers's Hypothesis 48 



Owen's Hyi)othesis 50 



Stevenson's Hypothesis 50 



Lesley's Hypothesis 50 



Discussion of Hypotheses based on Necessity of Metamorphism 52 



Anthracite can be formed by Contact with heated Rock 52 



Examples of Contact-alteration in New Mexico 52 



Example of Contact-alteration in Colorado 52 



Examples of Contact-alteration in Virginia and North Carolina 53 



Examples of Contact-alteration in New Zealand 53 



Alteration through Contact not invariable 53 



Objections to Rogers's Hypothesis 53 



Appalachians not cataclismic in Origin 54 



Erroneous Conclusions as to Relation of Disturbance to Amount of 



Volatile '^^5 



Neglect of Conditions observable in the individual Basins 56 



Discontinuity of Rogers's Line connecting anthracite and bituminous 



Basins ^^ 



True Statement of Relation of Disturbance to Amount of Volatile ... 56 



Influence of Dikes insignificant 57 



Columnar Structure not Evidence of loss of Volatile through Consol- 

 idation 5' 



VI-Bui,r,. Gkoi.. Soc. Am., Vor.. 5, 1893. (39) 



