National Geographic : 1893 Jul 10
88 C. D. Walcott-The Geologist at Blue Mountain. represented by the Cumberland and Shenandoah valleys. As this process continued and the river lowered its channel the Blue ridge began to take shape as a distinct feature in the land scape. Slowly but surely the softer beds were broken up, dis solved and carried away, and the harder beds of rock began to project above the ancient plateau. It was only the question of which beds of rock could the longer resist the forces of rain and frost to determine the location of mountains and valleys. We have thus hastily sketched the evolution of a portion of the continent and the evolution of one of its topographic fea tures as shown by the Blue ridge. This evolution has gone on everywhere. Every ridge, however small; every valley, whether shallow or deep, narrow or broad; every stream-channel all over the surface of the continent, has its history back in the past, and it is by the studies of the geologists that we learn something of that history. It is now nearly forty years since William B. and H. D. Rogers discovered many elements of the structure of the Appalachian mountains; but it was not until within the last few years that the means of correlating and thus interpreting more accurately the structure of the various mount ains formed by the lower and oldest series of the sedimentary rocks have been obtained. During the deposition of the 40,000 feet of sediments in the Appalachian trough many millions of invertebrate animals lived and died along the shore and on the sea-bed. Those that lived in the earlier epochs became extinct and new forms succeeded them, and these in turn were succeeded many times during the vast interval between the first deposit and the closing one before the epoch of the last Appalachian uplift and folding. The re mains of the various groups of life now afford the data by which the geologist correlates the various disturbed and often separated masses and determines what were their original relations to each other. There are hundreds of local details yet to be studied and in terpreted, and the work will be done by those who love to study the record of creation in the fragmentary book of nature, where all is written that we know of the past before barbaric man began his imperfect record by myth and legend.
1894 Jan 31
1893 May 05