Introduction to Geology. 75 
mits of hills, and remain solitary remnants of strata once con- 
tinuous, and interesting memorials of past revolutions. 
Among other proofs of the recurrence of such revolutions, 
in an earlier state of the globe, may be classed those breccious 
rocks and conglomerates which are composed of the fragments 
that originally occupied, or yet partially occupy, remote situ- 
ations. ‘The effects of a destructive power, as exhibited in the 
abruption of escarpments and the excavation of defiles, are 
also manifested by the reproduction of new rocks from the 
debris; and it has been further remarked, that these conglo- 
merate rocks bear marks of a similar destructive agency, 
occurring at some period subsequent to their consolidation. 
The tertiary formations also exhibit proofs of similar cata- 
strophes, in the alternation of marine and fresh-water strata, 
and in the mingled accumulations of animal and vegetable 
remains derive od both from the sea and the land.  * Life, 
therefore,” observes M. Cuvier, “has been often disturbed on 
this earth by terrible events: calamities which, at their com- 
mencement, have, perhaps, moved and overturned, to a great 
depth, the entire outer crust of the globe; but ich since 
these first commotions, have unifor mly noted at a less depth, 
and less generally. © Numberless living beings have been the 
victims of these catastrophes; some have been destroyed by 
sudden inundations, others have been laid dry in consequence 
of the bottom of the seas being instantaneously elevated. 
Their races even have become extinct, and have left no me- 
morial of them, except some small fragments which the natu- 
ralist can scarcely recognise. Such are the conclusions which 
necessarily result from the objects that we meet with at every 
step of our enquiry, and which we can always verify from 
examples drawn from almost every country. Every part of the 
globe bears the impress of these great and terrible events so 
distinctly, that they must be visible to all who are qualified to 
read their history in the remains which they have left behind.’ 
Diluvium. 
Over a large portion of the surface of our island, particu- 
larly towards the south and east, is spread a covering com- 
posed of the fragments of rocks, clay, sandstones, and chalk ; 
which debris, or broken portions, were evidently brought 
thither, and were irregularly accumulated, by means of pro- 
digious currents which swept over the face bE the earth. These 
appearances are confirmatory of the Mosaic account of the 
deluge, and by such an agency alone can these phenomena be 
adequately accounted for. The catastrophe appears to have 
