BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 18, pp. 449-476, PLS. 49-52 DECEMBER 17, 1907 



OEIGIF AND SIGNIFICANCE OF THE MAUCH CHUNK 



SHALE* 



BY JOSEPH BARRELL 



(Presented in abstract before the Society December 26, 1906) 



CONTENTS 



Page 

 Part I. Observatious bearing on the problems of origin 449 



Introduction 449 



General description of the Mauch Chunk formation 450 



The Mauch Chunk of the anthracite coal basins 453 



Stratigraphic characters 453 



Inorganic evidences of subaerial exposure 456 



Organic evidences of subaerial exposure 460 



Part II. Inferred conditions of origin 462 



Previous opinions 462 



Inferences as to geographic conditions of origin 463 



Floodplain origin of the Mauch Chunk 463 



Relations of laud and sea 463 



Relations of the delta, plain to regions of erosion 468 



Character of the delta surface 468 



Inferences as to climatic conditions 469 



Introductory statement 469 



Chemical and structural evidences as to climate 469 



Organic evidences as to climate 472 



Conclusions and comparisons 474 



Part I. Observations bearing on the Problems of Origin 



INTRODUCTION 



A discussion of the nature of geographic and climatic control of sedi- 

 mentation has been previously made by the writer in order that the 

 origin of certain specific formations might be dealt with, and the 'present 

 paper on the interpretation of the. Mauch Chunk follows these previous 

 articles in logical sequence, f 



* Manuscript received by Secretary of the Society from Censor October 28, 1907. 



t Relative geological Importance of continental, littoral, and marine sedimentation. 

 Journal of Geology, vol. xiv, 1906, pp. 316-356, 430-457, 524-568. 



Relations between climate and terrestrial deposits. Presented before the Geol. Soc. 

 Am. December 26, 1906. Printed in abstract in the Proc. Geol. Soc. Am. 



XXXIX— B0LL. Geol. Soc. Am., Vol. 18, 1906 (449) 



