94 Thaxsactioxs of the American Institute. 



ancient ocean bed ; wliile the determining causes of their elevation 

 existed long anterior to the production of the mountains themselves. 

 At no point, nor along any line between the Apalachian and Rocky 

 mountains, could the same forces have produced a mountain chain, 

 because the materials of accumulation were insufficient ; and though, 

 we may trace what appears to be the gradually subsiding influence 

 of these forces, it is simply in these instances due to the paucity of 

 material upon which to exhibit its effects. 



I have endeavored to trace with some degree of detail, the pro- 

 cesses which have been going on through all this palaeozoic or ancient 

 life time, as we know these formations in geology by that designa- 

 tion. I have shown you the results of the long continued action of 

 gentle operations, without the intervention of those violent move- 

 ments of the interior forces, or of catastrophes which are appealed 

 to for the explanation of the existing conditions. In this view, the 

 history of continental formation may lose some of its exciting interest, 

 but it seems to me to lead to more rational opinions concerning the 

 geological structure of this part of our continent, and of the laws 

 which govern the distribution and accumulation of sediments upon 

 the ocean bed, giving us finally the rock formations in which we find 

 the record of life upon our earth from its beginning. 



It may be said that these observations are too limited to be made 

 applicable to other continental areas or other mountain chains ; but the 

 same features, to a very large extent at least, are presented in tlie old 

 Laurentian continent and its mountain ranges. It would hence 

 appear safe to conclude that the laws, so clearly operating here, have 

 operated similarly elsewhere, and that the process of continental evolu- 

 tion and of mountain elevation has been the same in other countries 

 as in our own. • 



Turning to the map before us, you will observe that the eastern 

 shore of our continent is skirted by a difierent color. You have 

 likewise, in the Connecticut valley, and along New Jersey, Pennsyl- 

 vania, Maryland, Virginia, North and South Carolina, a belt of 

 different color, separate from the coast-line belt, the whole indicating a 

 series of newer formations than those forming the great eastern conti- 

 nental area. This coast-line belt widens to the southward, and 

 presents a broad area across the southern border of the United States. 

 It extends up the valley of the Mississippi, as far as the mouth of the 

 Ohio, westward, througli Arkansas and Missouri, and in a broad belt 

 far up into Minnesota. It occupies the great valley and plateau of 



