498 
SILTJKIA. 
[Chap. XX. 
has never worn away any portion of the rock. The clear inference, then, 
in these and countless other instances is that rivers in all such cases simply 
flow in the gorges and depressions prepared for them by previous geological 
disturbances. 
There is yet another subject of discussion in the physics of geology on 
which I must express my dissent from the views of some of my most 
esteemed associates, whose other works I highly admire. In a preceding 
page I have expressed my belief that, in the earlier or Palaeozoic times, the 
lands never rose into very lofty mountains, nor were the sea-bottoms so 
deep as in the present day. Had the present diversified outline of the 
earth, or even an approach to it, existed in the Palaeozoic era, most 
assuredly the same groups of animals and plants could not have been 
spread as they were over such enormous areas as those over which we find 
their remains ; for the deep sea is to all ' Laminarian ' marine creatures 
as impassable an obstacle as the high mountains are to the spread of 
land animals. 
Again, if very lofty mountains had existed in Palaeozoic times, we should 
somewhere find distinct proofs that snow and glaciers then prevailed ; but 
of this phenomenon I cannot admit that valid proofs have yet been given. 
The discovery by Professor Ramsay of some smoothed and striated stones at 
one place among the Permian rocks of England cannot, I think, be held as a 
proof of true glacier- action*, seeing that there are other agencies by which 
such scratches may have been produced. We must recollect that the Per- 
mian period was one of igneous activity and great disturbance; and in such 
a state of nature we can very well imagine how, by the friction of rock- 
masses against each other (as in one of the elevations of the adjaeent Malvern 
Hills), such striae might have been produced. Still less can I admit that 
the blocks in the much older conglomerate of the Old Red Sandstone of 
Scotland were transported by ice ; for all these are purely local conglome- 
rates, piled up against, or lying upon, the older rocks out of which they 
have been compounded. They are therefore, in my opinion, simply the 
results of some of the powerful earthquakes, dislocations, and debacles 
which, as I contend, have affected the earlier crusts of the earth, and 
thus left them as detrital materials almost in situ. 
Imbued with this belief, I must also demur to the opinion which might 
be derived from an inspection of the sections of my distinguished friend 
Professor Ramsay, when he carries up to extreme heights those dotted 
theoretical lines over his actual and truthful sections, by which he indi- 
cates the probable altitude of mountains in ancient geological times, by 
supposing the upward continuation of strata which have really been trun- 
cated near the surface of the earth. If the highly inclined lines of strata 
on the opposite sides of a broad dome of older rock really continued in an 
* Compare Professor Ramsay's Memoir on the subject, Quart. Journ. Geol. Soc. vol. xi. pp. 185 &c. 
