98 Transactions of the American Institute. 



molten matter. So far as we have any knowledge of the materials in 

 the interior of the globe, they appear to ns only as trap-dykes ; and 

 as these occnpy but a very small area npon the surface, they may 

 have been derived from a very moderate depth. Beyond this the 

 original nucleus of our planet which has been so much written about 

 in geology, has produced no effect upon the surface of the earth ; 

 neither upon its mountain chains, or any other of the great features 

 of the continents. I have shown that in the formation of this 

 continent, the materials composing it have been derived from the 

 breaking down of pre-existing lands transported and deposited 

 along certain lines, or spread out in mid-ocean and there accumu- 

 lating more uniforml3^ The inequalities upon the surface of the 

 country ai'e not due to any special action along these lines of 

 elevation. Those mountain ranges, whether the Rocky mountains 

 of the west, the Apalachian chain of the east, or any other range 

 of mountains, so far as we know t]iem, are not due to the action 

 of any special interior forces operating along these lines, but only 

 to the greater accumulations on the bed of the ocean in tliat 

 direction, as 1 have shown you more especially in regard to the 

 Apalachian chain. Everywhere the same law has prevailed : the trans- 

 porting power of the ocean has deposited, in the line of its currents, 

 larger quantities of material which have subsequently been elevated 

 in continental form. The elevation of tlie eastern part of the North 

 American continent in no way connected the production or elevation 

 of mountain chains farther than they constitute a portion of the 

 continental mass. Going back, then, step by stej), from the more 

 recent to the earliest times in relation to which we have any 

 evidence whatever, we have no proof that the violent action of the 

 interior forces of our globe has produced any one of the great features 

 of its surface, beyond the volcanic mountains. This idea of a great 

 primary nucleus is onl}'" theoretical. From the earliest geological 

 history, inferring, from the trend of stratified deposits, we learn that 

 the ocean currents have had essentially tlie same direction as at the 

 present time, moving from the northward to the southward, and that 

 the zones of greatest accumulation and of the greatest elevation of 

 our continent have been everywhere coincident from the beginning. 



