ORIGIN OF THE APPALACHIAN COAL STRATA, &C. 433 



A.N Inquiry into the Origin of the Appalachian Coal 

 Strata, Bituminous and Anthracitic. By Henry D. 

 Rogers^ Professor of Geology in the University of Pennsyl- 

 vania, Philadelphia. 



INTRODUCTION. 



The design of the present paper is, to exhibit, in a condensed 

 shape, some of the most characteristic phenomena of the great 

 coal formation of the Appalachian region of the United States, to 

 develope the laws which regulate the distribiition and order of 

 succession of the strata, and to discuss the theory of their origin. 

 But it is not intended to embrace a detailed description of our 

 extensive and diversified basins, a full account of which is re- 

 ' served for a future opportunity. 



In prosecuting this investigation, though I have relied princi- 

 pally on my own observations, made during several years past 

 in Pennsylvania and Ohio, and on those of my corps of assist- 

 ants, attached to the geological survey of the former State, I have 

 received much valuable information concerning western Virginia 

 from my brother. Professor William B. Rogers, whose researches 

 have enabled him to test the correctness of most of my conclu- 

 sions. To him, and to Mr. C. Briggs, now connected with the 

 survey of Virginia, but formerly with that of Ohio, I am indebt- 

 ed for my knowledge of the range and outcrop of the great Pitts- 

 burg seam in those States ; while to my brother I owe the op- 

 portunity of making a highly instructive comparison in detail, of 

 the coal strata of Pennsylvania with those of western A^irginia. 

 For some data respecting the positions of the limestones of the 

 Ohio coal measures, I wish to acknowledge my obligations to 

 the laborious paper of Dr. Hildreth, in the twenty-ninth volume 

 of the ' American Journal of Science.' I have made a similar 

 use of the Reports of Messrs. Briggs, Whittlesey, and Foster, on 

 the geology of the same State. My attention was first directed 

 to the marine character of some of the Appalachian coal strata, 

 by the description of two or three fossils from the carboniferous 



