Ch. IX.] 
RECAPITULATION. 
117 
thousand feet above the level of the sea, and this elevation im- 
plies an extraordinary modification in the state of the earth's 
crust at some unknown depth beneath the tract so upheaved. 
5thly. The most probable hypothesis in regard to the nature 
of this change, is the successive generation and forcible intru- 
sion into the inferior parts of the earth's crust of lava which, 
after cooling down, may have assumed the form of crystalline 
unstratified rock, such as is frequently exhibited in those 
mountainous parts of the globe where the greatest alterations 
of level have taken place. 
6thly. Great inequalities must have been caused on the 
surface of the new-raised lands during the emergence of the 
newer Pliocene strata, by the action of tides, currents, and 
rivers, combined with the disturbing and dislocating force of 
the elevatory movements. 
7thly. There are no features in the forms of the valleys and 
sea-cliffs thus recently produced, which indicate the sudden 
rise of the strata to the whole or the greater part of their pre- 
sent altitude, while there are some proofs of distinct elevations 
at successive periods. 
8thly. We may infer that the species of terrestrial and 
fluviatile animals and plants which now inhabit extensive 
districts, formed during the newer Pliocene era, were in exist- 
ence not only before the new strata were raised, but before 
their materials were brought together at the bottom of the sea. 
