BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



VOL. 15, PP. 267-282, PL. 11 JUNE 24, 1904 



DEPOSITION OF THE APPALACHIAN POTTSVILLE* 



BY DAVID WHITE 



(Read before the Society January i, 1904) 



CONTENTS 



Page 



Introduction 267 



The Mississippian-Pennsylvanian unconformity 268 



Figure of the basin and thickness of Pottsville sediments 268 



Development of the basin 271 



General features 271 



Pocahontas deposition 271 



Horsepen-Raleigh-Bon Air overlap 272 



Sewell-Sharon deposition , 272 



Sharon overlap 273 



Post-Sharon transgression 274 



Subsidence and extension of the basin under loading 274 



Character and origin of the basin 274 



Position of early Pottsville axis 275 



Eastern margin of the basin 276 



Amount of Pottsville sedimentation 277 



Arches or barriers within the basin , 278 



Physical evidence of the Pottsville transgression. 279 



Summary of Appalachian Pottsville history. 280 



Introduction 



The purpose of this paper is to present certain general facts respecting 

 the conditions of Appalachian sedimentation which have come to light 

 chiefly through the study of the Pottsville floras. A portion of the 

 results of this study, concerning in particular the nature of the basal 

 Pottsville unconformity and the measures of relative sedimentation, 

 has already been presented in the writer's papers on the fossil plants. 

 The more advanced stage of the paleobotanical work now permits the 

 revision of certain of the conclusions earlier published while further 

 extending their scope in the realm of the physical geography of the 



* Published by permission of the Director of the U. S. Geological Survey, 

 XXXV— Bull. Geol. Soc. Am., Vol. 15, 1903 (267) 



