OP ARTS AND SCIENCES : MAY 28, 1867. 311 



titled " Geology of Pennsylvania, Government Survey ; with a General 

 View of the Geology of the United States, Essays on the Coal Forma- 

 tion and its Fossils, and a Description of the Coal Fields of North Amer- 

 ica and Great Britain." This great woi*k is contained in three royal 

 quarto volumes, illustrated by forty-five sketches of scenery, forty-seven 

 geological sections, two plates of columns of strata, twenty-three plates 

 of coal fossils, and seven hundred and seventy-eight wood engravings 

 of views and diagrams of coal-beds, &c., and accompanied by a general 

 geological map of the State, a special map of the anthracite coal- 

 basins, and two large sheets containing the nine general sections, eluci- 

 dating the geological map. 



During the early progress of this work he produced, in conjunction 

 with his brother, William B. Rogers, the well-known memoir " On the 

 Physical Structure of the Appalachian Chain," unfolding certain dy- 

 namical laws which have regulated the elevation of mountain chains. 

 About the same time (1842) he published an elaborate paper on the 

 origin of the Appalachian coal strata, bituminous and anthracitic, con- 

 taining much original observation and important speculative views ; 

 his brother pursuing a parallel system of investigations in Virginia, 

 where the formations are identical with those of Pennsylvania. The 

 result of the labor of these two brothers, carried on for ten years 

 together, was the grand discovery of the structural unity of central 

 North America, between the Appalachian chain and the Eocky 

 Mountains, the great lakes and the Delta inclusive ; a ftict of such im- 

 portance that it must serve in future as a guide to all general reseai'ch- 

 es ; since it is not reasonable to suppose that so large a portion of the 

 earth's surface should have been formed in any other than the normal 

 mode. Occupying at this time the chair of Geology in the University of 

 Pennsylvania, he gave instruction in that science in the intervals of 

 his labors on the State Survey. He also delivered courses of lectures 

 at the Lowell Institute and elsewhere ; on all such occasions showing 

 that readiness and felicity of diction, without the use of notes, for 

 which, he had always been remarkable. 



He was one of the founders, and an early President, of the American 

 Association of Geologists, which, after an active and most useful career, 

 expanded into the American Association for the Advancement of Sci- 

 ence. Although chiefly devoted to geological research. Professor Rogers 

 paid much attention to those sciences of which geology is the extended 

 application, — Natural History, Climatology, and Physical Geography. 



