500 
SILUEIA. 
[Chap. XX. 
sophy in exactly the same manner, and to the same degree, as the belief 
that a clock constructed with a self-winding movement may fulfil the 
expectations of its ingenious inventor by going for ever. It must be 
admitted," he adds, " that many geological writers of the Uniformitarian 
school, who in other respects have taken a profoundly philosophical view of 
the subject, have argued in a most fallacious manner against hypotheses of 
violent action in past ages." And then, in support of his o wn views, he asks 
these pertinent questions : "Is not this, on the whole, in harmony with 
geological evidence, rightly interpreted ? Do not the vast masses of basalt, 
the general appearance of mountain-ranges, the violent distortions and 
fractures of strata, the great prevalence of metamorphic action (which 
must have taken place at depths of not many miles, if so much), all agree 
in demonstrating that the rate of increase of temperature downwards must 
have been much more rapid, and in rendering it probable that volcanic 
agency, earthquake-shocks, and every kind of so-called plutonic action have 
been, on the whole, more abundantly and violently operative in geological 
antiquity than in the present age?"* 
Seeing that the view I long ago adopted solely from an appeal to geologi- 
cal phenomena has since been supported on these independent grounds 
by the reasoning of one of our leaders in physical science, I return to 
the consideration of the main object of this work, or the History of the 
Palaeozoic Ages — a subject happily on which all geologists are, I trust, 
now agreed. 
If we reflect upon the succession presented to us in the primeval deposits, 
we have, I repeat, cumulative evidence to prove that the wide-spread dif- 
fusion of the same types of animal and vegetable life was due to a former 
temperature and outline of the surface essentially different from those 
of our day. To whatever extent continents and islands may have existed 
during those long early periods, and however we may speculate on the 
extent of pristine shores, it seems certain that the lands accessible to our 
research increased in size very considerably at the close of the Devonian 
period, and especially in the Carboniferous times. In those days the very 
same species of marine animals lived from the latitude of Spitzbergen 
to the parallels of Peru and Australia f. Then also vast low deltas 
stretched out in every direction, bearing a uniform terrestrial vegetation, 
absolutely identical over at least half the globe. Many of the ancient Tree- 
ferns must have grown on tracts little above the water ; and jungles larger 
than Britain must have been successively and repeatedly submerged and 
renewed, forming lands loaded in time with the accumulated vegetation 
* Phil. Mag. ser. 4. vol. xxv. p. 9. They also occur in Australia: see M'Coy, Ann. 
t The Peruvian Ancles, and other parts of the Nat. Hist. 1847. For the numerous forms of Car- 
Cordillera ranging into California, have afforded boniferous types in Spitzbergen see Quart. Journ. 
several species of Carboniferous Mollusca iden- Geol. Soc. vol. xvi. pp. 439 &c, and the results of 
tical with British forms, and I have myself found the late Swedish Expedition, Trans. Acad. Stock- 
the same in the Ural Mountains: see 'Russia- holm, 1866. 
in-Europe and the Ural Mountains,' vol. i. p. VS. 
