570 
ELEMENTS OF GEOLOGY. 
The like observations may be extended to nearly the whole 
of Europe, for, since the commencement of the Eocene Period, 
the entire European area, including some of the central and 
very lofty portions of the Alps themselves, as I have else¬ 
where shown,* has, with the exception of a few districts, 
emerged from the deep to its present altitude. There must, 
therefore, have been at great depths in the earth’s crust, 
within the same period, an amount of subterranean change 
corresponding to this vast alteration of level affecting a 
whole continent. 
The principal effect of subterranean movements during the 
Tertiary Period seems to have consisted in the upheaval of 
hypogene formations of an age anterior to the Carboniferous. 
The repetition of another series of movements, of equal vio¬ 
lence, might upraise the plutonic and metamorphic rocks of 
many secondary periods; and, if the same force should still 
continue to act, the next convulsions might bring up to the 
day the tertiary and recent hypogene rocks. In the course 
of such changes many of the existing sedimentary strata 
would suffer greatly by denudation, others might assume a 
metamorphic structure, or become melted down into plutonic 
and volcanic rocks. Meanwhile the deposition of a great 
thickness of new strata would not fail to take place during 
the upheaval and partial destruction of the older rocks. 
But I must refer the reader to the last chapter but one of 
this volume for a fuller explanation of these views. 
Plutonic Rocks of Cretaceous Period. —It will be shown in 
the next chapter that chalk, as well as lias, has been altered 
by granite in the eastern Pyre¬ 
nees. Whether such granite be 
cretaceous or tertiary, can not 
easily be decided. Suppose 5, c, 
c?. Fig. 618, to be three members 
of the Cretaceous series, the low¬ 
est of which, has been altered 
by the granite A, the modifying 
influence not having extended so far as c, or having but 
slightly affected its lowest beds. Now it can rarely be 
possible for the geologist to decide whether the beds d 
existed at the time of the intrusion of A, and alteration of 
h and c, or whether they were subsequently thrown down 
upon c. But as some Cretaceous and even tertiary rocks 
have been raised to the height of more than 9000 feet in 
the Pyrenees, we must not assume that plutonic formations 
of the same periods may not have been brought up and ex- 
* See map of Europe, and explanation, in Principles, book i. 
Fig:. 618 . 
