S4 PALEONTOLOGY OF NEW-YORK. 



line rocks are, to a large extent at least, confessedly of the age of the 

 Coal measures, and the anthracitic plumbago of Worcester (Massachu- 

 setts) is recognized as of the same age as the anthracite of Rhode- 

 Island. 



We may expect that changes equally great will yet take place in the 

 opinions of geologists regarding other mountain ranges. It is now a long 

 time since the supposed primary origin of the Alps has given place to 

 more rational views, and all geologists admit that the summits of these 

 mountains are composed of the more modern geological formations. If the 

 fundamental rocks of the Alps are of palaeozoic age, and the sequence 

 has been continued, even with some interruptions, to the end of the 

 Jurassic period or later, it is no wonder that there are high summits, 

 for the accumulation must have been enormous ; and if to the Liassic 

 and Jurassic we add the Cretaceous and Tertiary, we may get moun- 

 tains of the elevation of the Himalayas. For I hold that no mountains 

 of this elevation can occur without the long continued accumulation of 

 sediments ; sediments, not simply marking this altitude, but vastly 

 more, for there is doubtless as much of the mass below the level of the 

 sea as above it. This view we find applicable to the Appalachians, and 

 it must be a necessary condition of mountain elevation. Moreover, I 

 believe it to be true, and a legitimate inference from the facts and ge- 

 neralizations already stated, that all mountains of great height will 

 be found to embrace the newer geological formations in their mass*. 



• In attributing mountain elevation to the action of subterraneous upheaving forces, no satisfactory- 

 explanation has been given to account for the much more powerful influence exerted in one 

 country or along one line, than in another. It will not meet the inquiry to say that the former or 

 earlier operations of this class were more powerful than the later; for the reverse is true. If we look 

 at the oldest or Laurentian and Adirondack mountains, the greatest elevations are only about five 

 thousand feet alxjve tide water, while the palaeozoic Appalachians are little more than six thousand; 

 and we have very good evidence that the country occupied by these ranges was the earliest continen- 

 tal land. When we go westward to the Rocky mountains, we find higher elevations above tide water; 

 but we also have newer formations, showing that the final elevation of that part of the country was 

 accomplished at a later period than that of the eastern zone. Whether there may have been a previous 

 elevation of this part of the country, and a second submergence, does not affect the inferences in the 

 present case. 



