148 Prof. Rogers 9 s Address before the 



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Hall, Mather, and Vanuxem, in New York, and of Hall, Locke, and 

 Owen, especially of the latter, in the Western States, have taught us 

 many curious facts concerning the modifications which the more per- 

 sistent strata undergo in this westward range from the Hudson to the 

 Mississippi. The changes which the same mineral deposits experience 

 in their long course from the Hudson to Alabama, have been exam- 

 ined by my brother and myself, and have already exposed to us some 

 beautiful general laws of variation, which we believe will throw light 

 on the character of the physical conditions and movements that accom- 

 panied the diffusion of these ancient sediments. As the strata gen- 

 erally reascend to the surface several times across a wide belt in the 

 mountain chain, especially in Pennsylvania and Virginia, it is practica- 

 ble to study the variations of type, not in one direction merely, as from 

 N. E. to S. W., also from S. E. to N. W., or seawards as respects 

 the coast of the ancient Appalachian ocean. In so many places, both 

 in the mountains and the great plains of the Western States, are the 

 shore and the deep sea deposits of that ancient ocean lifted to the sur- 

 face by artificial flexures, so entirely in each of its many successive 

 flows with the whole of the once living tribes that they supported, 

 brought into contact with our hands for exact measurement, within 

 reach of our closest vision for minute inspection, or even microscopic 

 analysis, that the systematic and patient study of its contents, its sedi- 

 ments and organic fossils, now in progress, cannot fail to reward us 

 with a full disclosure of all that was striking in its history. 



Let us now turn to the progress recently made in developing the 

 palaeontology of this great Appalachian basin, in classifying and nam- 

 ing the formations, and in determining the relationship in age between 

 these and the palaeozoic strata of Europe. By the researches of Mr. 

 Conrad, Prof. Emmons, and Mr. Hall, in New York, and of Hall? 

 Owen, Troost, Locke, and Clapp, in the Western States, we are already 

 made familiar with the forms and the positions in the strata of perhaps 

 five hundred well characterized marine fossils, embraced in numerous 

 genera of trilobites, testacea, and corals. The labors of Hall and 

 Conrad, in bringing to light the chief part of these remains, have been 

 especially valuable. As Mr. Hall is devoting himself with great zeal 

 and signal success, to the fascinating study of the organic remains ol 

 New York, and as the geologists of other States are availing them- 

 selves of its clearly defined specimens for those comparisons, without 

 which little real progress can be achieved in the more refined enquiries 

 connected with our palaeontology, we may anticipate the speedy develop- 



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