THE WEST INDIAN BRIDGE. ii 



theme of this communication, is also important in establishing meth- 

 ods for determining similar great changes of land and ocean in other 

 regions in late geological times. 



Growth of the Science of Geomokphy. — The methods of in- 

 quiry belong to geomorphy, or the study of land forms. Geomorphy 

 is the outgrowth of topography, which was made a science fifty or 

 sixty years ago by Prof. J. P. Lesley and his coworkers. Its birth 

 is graphically described by the author himself: * " That the Euro- 

 pean Jura . . . had to wait for its elucidation until the American 

 Appalachians had been mapped may seem strange, but it admits of 

 easy explanation. In Pennsylvania, paleontology and detailed local 

 stratigraphy were impossible; we were untrained in both, . . . The 

 country was no ground for mineralogy; no rare and curious minerals 

 exist in it; it is a waste of sand, mud, iron, and limestone strata of 

 various textures and color in endless repetition; to know one was 

 to know all; to know it here was to know it every^vhere. Nothing 

 remained to study but dynamic forms; and these so numerous, so 

 grand, so variously grouped that they excited our perpetual enthu- 

 siasm, and led to infinite research; they supplied the place of fossil 

 forms, of forms of crystals, and of variations of mineral elements; 

 they were a world of the exhibition of the natural forces by itself, 

 and as such we took possession of it and settled in it as our fathers 

 did in the valleys themselves, and thus became not mineralogists, 

 not miners, not learned in fossils, not geologists in the full sense of 

 the term, but topographers; and topography became a science, and 

 was returned to Europe and presented to geology there as an Ameri- 

 can invention. The passion with which we all studied it is incon- 

 ceivable, the details into which it led us were infinite. . . . They 

 trained us to that fertility of fancy which precedes the ripening of 

 the constructive or geometric faculty, made to act upon the more 

 difficult problems of geology; while its generalizations were so vast 

 . . . that customary European local research . . . seemed tedious. 

 . . . The moment, therefore, that one of us beheld the ranges of 

 the Jura, with their combs and offsets, their vast escarpments, and 

 far-glittering white gaps, he was at home among friends, where 

 geologists, born among them, felt that they were strangers. For 

 the valleys of the Jura were filled with later formations full of fossils, 

 which the Appalachian valleys never are. There much is hidden, 

 here all is told. Fossils themselves in the Jura distracted study from 

 the topography." 



Geomorphy, like its antecedent, the science of topography, is 



* Manual of Coal and its Topography. By J. P. Lesley. 12mo, pp. 1-224. Pulilished 

 by J. P. Lippincott, Philadelphia, 1856. 



