EVOLUTION AND THE PRESENT AGE 263 
ions, there was a tendency to suppose that in earlier 
ages the agencies at work in modifying the earth’s 
surface must have been far more violent than at 
present. It was quite natural that people should 
think so. The changes which geology revealed were 
apt to be mighty changes ; layers of strata many miles 
in area wrenched out of place and perhaps turned up 
on edge, erratic blocks of stone carried thousands of 
miles from home in glaciers more than a mile in thick- 
ness, long stretches of sea-coast torn away by the rest- 
less waves, mountains bearing on their summits the 
telltale evidences that they had once been submerged 
in the ocean; all these things seemed to speak of 
gigantic displays of force like the wanton play of 
Titans and Asuras in the ancient mythologies. Still 
more was this view impressed upon the mind as the 
wonders of paleontology became gradually revealed to 
us. Here we were shown a succession of past ages, 
during which the aspect of things was totally different 
from what it is now. There was, for example, the age 
when the great coal measures were deposited, char- 
acterized by a dense and suffocating atmosphere, with 
vegetation generally as exuberant as that of modern 
Brazil, with colossal tree ferns abounding, but not a 
single deciduous tree or flowering herb in existence. 
That Carboniferous age had its day and vanished, leav- 
ing its vegetable wealth locked up in the bowels of 
the earth to heat the houses and propel the engines 
of men in this age of ours. By and by there was a 
Jurassic age, when reptiles were the lords of creation, 
the bulkiest animals ever seen upon earth, yet with 
brains too small to.do more than guide their clumsy 
movements. These were the days when the Atlanto- 
