84 
PALAEONTOLOGY 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 view.s, 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 above 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. 
