W. J. Sofias — On Evolution in Geology. 
5 
surface ; the difference in temperature might not be very great, but 
it would exist. From the increased rainfall would necessariiy follow 
a more rapid corrosion of the general surface of the land, and a 
speedier degradation of its general level. The sculpturing of hills 
and valleys and the delivery of detritus to the sea must liave pro- 
ceeded at a swifter rate ; and indeed all the activities of rain and 
rivers would be stimulated to relatively greater energy. 
3. Subterranean Waters . — Not only would the amount of these be 
augmented by the increased rainfall, but they would be influenced 
by the higher temperature of the earth’s crust ; thus in the present 
period percolating water must descend on the average 51 feet below 
the zone of constant temperature in order to rise 1° in temperature ; 
4,000 years after the permanent incrustation of the earth, the same 
descent would be accompanied by an elevation of 5° in temperature. 
4. Marine Denudation. The Waves . — The difference of tempera- 
ture which produces the rainfall also drives the winds in their 
courses, just as truly as the difference in temperature between the 
boiler of a steam engine and the external air drives the piston. 
Augment the difference and the winds will flow faster and more 
violently, just as certainly as fresh fuel will urge the engine with 
greater activity. Thus the denudation accomplished by the winds 
will also be accelerated, especially that disintegration of sea-cliffs 
which they produce indirectly. For it is the winds ruffling the ocean 
which produce the sea- waves, and it is the energy of these directed 
to the battering down of the cliffs along every coast-line which pro- 
duces a great part of the work of marine denudation. 
Tides . — These are due to the rotation of the earth between the 
attracting bodies of the sun and moon, and since this rotation must 
have been more rapid the further back we recede in time, so must it 
have conferred greater energy on the actions of the tides. Let the 
velocity of the earth’s rotation be doubled, and the tides will rise 
four times instead of twice in every twenty-four hours, and with 
greater frequency will attain also greater velocity. But it is the 
tides and tidal currents which are, amongst others, the most per- 
sistent agents in coast-line transportation ; and thus the detritus 
produced with increased rapidity by the disintegrating actions of 
the rain and waves, will be with corresponding rapidity carried 
away to preserve the coast-line constantly exposed to renewed decay. 
Marine Currents. — All these, excepting those produced by the 
tides, are ultimately due to differences in temperature on which 
the winds also depend, and thus will likewise flow with accelerated 
velocity, and consequently their influence as transporting agents 
will be correspondingly exalted. 
Deposition . — The rate of deposition is always directly proportional 
to the rate of denudation, and may be said at any particular time to 
equal it. Thus any increase in the rate of denudation will be 
necessariiy accompanied by a corresponding increase in the deposi- 
tion of Sediment. If we look for any direct proof of this, there is 
but little to be found. Prof. Phillips has shown that the proportion 
of the number of fossil species to the thickness of its strata con- 
