Chap. XX.] 
OLD THEKMO-DYNAMIC CAUSES. 
499 
unbroken curve, the upheaved Palaeozoic rocks must occasionally have con- 
stituted mountains as high as any existing snowy mountains of the present 
period *. Such a view of our subject cannot, it seems to me, for many 
powerful reasons, be sustained. Thus the plants and animals which lived 
in the subsequent Devonian and Carboniferous periods all clearly indicate 
that those deposits were formed under a warm temperature, and were not 
accumulated in cold climates. 
Again, if we are to believe in the existence of such lofty mountains in 
the oldest periods, we must suppose that a warm climate prevailed in the 
low countries and that glaciers existed only at great heights ; and if so, 
how can we rationally explain the entire destruction and disappearance 
of such gigantic masses of solid matter as must have taken place over 
such vast areas ? On the other hand, if we restrict our conception of 
such dislocations and upheavals to their having simply affected those 
portions of the strata which, anterior to their rupture, were more or less 
horizontal, and that they never were raised into the lofty domes hypo- 
thetically assigned to them, we can then readily believe how inundations 
and other agencies through long ages, may have swept away such restricted 
accumulations of broken materials. 
Before I quit the consideration of those former proofs of a greater inten- 
sity of former causation, I may well rejoice in knowing that my opinions 
as a practical geologist, and derived solely from facts, have been sup- 
ported by that eminent mathematician Sir William Thomson, entirely on 
the principles of thermo- dynamics, which, as he says, have been over- 
looked by those geologists who uncompromisingly oppose all paroxysmal 
hypotheses. In a memoir on the " Secular Cooling of the Earth" f, he has 
shown that " the solar system cannot have gone on, even as at present, for 
a few hundred thousand or a few million years without the irrevocable 
loss (by dissipation, not by annihilation) of a very considerable proportion 
of the entire energy initially in store for sun-heat and for plutonic action. 
In another memoir % he has shown that probably the sun has been sensibly 
hotter than now : " Hence (he observes) geological speculations assuming 
somewhat greater extremes of heat, more violent storms and floods, more 
luxuriant vegetation {ex. gr. the Coal-period) are more probable than those 
of the quietest or Uniformitarian school." After showing the secular 
amount of loss of heat from the whole earth, and repudiating the chemical 
hypothesis that the substances combining together may be again separated 
electrolytically by thermo-electric currents due to the heat generated by 
their combination, and thus the chemical action and its heat continued in 
an endless cycle, — this, he says, " violates the principles of natural philo- 
* See for instance the Mem. of Geol. Survey, evidence of the greater intensity of causation in 
vol. i. pp. 297 &c. plates 4 & 5, and vol. iii. pi. 28. former periods. 
If the ingenious views of my distinguished friend t Trans. Eoy. Soc. Edinburgh, vol. xxiii. pt. 1, 
be explained by calling in enormous dislocations and Phil. Mag. ser. 4. vol. xxv. pp 1 &c. 
and denudations, these certainly would be plain J Macmillan's Magazine, March 1862. 
2x2 
