SKETCH OF HENRY DARWIN ROGERS. 261 



William B. Rogers, the well-known memoir, On the Physical 

 Structure of the Appalachian Chain, unfolding certain dynamical 

 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 anthra- 

 cite, containing much original observation and important specu- 

 lative views, his brother pursuing a parallel system of investiga- 

 tion 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 Appa- 

 lachian chain and the Rocky Mountains, the Great Lakes, and the 

 Delta inclusive, a fact of such importance that it must serve in 

 future as a guide to all general researches, since it is not reason- 

 able to suppose that so large a portion of the earth's surface 

 should have been formed in any other than the normal mode. . . . 

 Prof. Rogers 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 Science. 



"Although chiefly devoted to geological research, he paid 

 much attention to those sciences of which geology is the extended 

 application natural history, climatology, and physical geog- 

 raphy." 



His work was appreciated abroad as well as at home. He 

 received the degree of LL. D. from Trinity College, Dublin ; was 

 elected a Fellow of the Royal Society (London), and of the Royal 

 Society of Edinburgh, and of many other important societies. 

 He was also for two years the President of the Philosophical 

 Society of Glasgow. He became one of the conductors of the 

 Edinburgh New Philosophical Journal, and was associated with 

 Sir William and A. K. Johnston in the publication of maps of 

 physical geography and geology, particularly of a geological map 

 of the United States and a chart of the arctic regions in their 

 Physical Atlas. 



The anniversary address of the President of the Geological 

 Society (London), in a notice of Prof. Rogers, contains the fol- 

 lowing estimate of his work as a geologist : 



" While employed upon his great survey he had contributed 

 to the Proceedings of this society a paper entitled Some Facts in 

 the Geology of the Central and West Portions of North America. 

 In this address he dwelt especially on those great features 

 which he had elaborated in his survey, the disturbance of the 

 Palaeozoic rocks of the Appalachian chain, ' a stupendous undula- 

 tion or wavelike pulsation, the strata being elevated into perma- 

 nent anticlinal and synclinal flexures, remarkable for their wave- 



