C.—GEOLOGY. 107 
the vital importance to the animal evolution of the world in general, and 
to the welfare of man in particular, of this step forward. It was followed 
by great changes in the insect world, by the rapid production of herbi- 
vorous mammals endowed with speed, great migratory powers, special 
dental and other anatomical adjustment to the new foods, and the insti- 
tution in their herds of a discipline, subordination, and leadership which 
are almost tribal. These last qualities were rendered doubly necessary 
by the consequent rapid development of carnivora, and the need for scrap- 
ping passive and even active means of defence in order to secure the power, 
_ speed, and reserve necessary to follow their food harvests over great 
_ stretches of country. At the same time the habits and instincts thus 
brought about were those which man, by domestication, has been able to 
turn to his own ends. Thus at a blow, as the outcome of this stage of 
Tertiary evolution, there became available for mankind not only his chief 
plant food and drink, his luxuries as well as his necessaries, but his chief 
animal foods, together with his aid from the speed, strength, service, and 
endurance of the animals which he domesticated and to which he assumed 
the position of leader of the herd. 
But while with the aid just described it was possible for mankind to 
progress far on the road of civilisation, progress would have been stopped, 
and as a matter of fact was seriously retarded, until the discovery and 
utilisation of the solar energy stored up in the earth’s crust during the 
Carboniferous and subsequent Periods in the form of coal and other fossil 
fuels. The very exceptional conditions, climatal, geographical and 
botanical, requisite for coal formation, occurred all too seldom in 
geological history ; but it has so happened that few areas of the earth are 
devoid of coal belonging to one Period or another; and the shaping of 
kingdoms and dominions has been such as to include supplies of fuel in 
most of them. Whatever may be the main sources of energy in the future, 
radiant, intratelluric, hydraulic, tidal, atomic, we have been largely 
dependent in the past, and probably shall continue to depend for many 
years to come, on that portion of the solar energy stored up by vegetation, 
and especially on that preserved in the earth-crust in the form of coal. 
But again civilisation must have been greatly hampered or driven into 
_ adifferent course but for the agencies which have sorted out fromthe medley 
of materials of which the earth is composed, simple compounds or aggre- 
gates of compounds, or in rarer cases simple elements, in such a form that 
they are available for human use without the expenditure on them of 
excessive quantities of energy. The concentration of metalliferous ores, 
_ salines, and the host of other mineral resources has made perhaps the most 
important contribution of all to the latest stage—in good and evil—attained 
by civilisation. 
Finally, doubt may be expressed whether man could have attained his 
present position if he had not made his appearance comparatively soon 
after a period of intense earth activity, when broad areas of newly raised 
sediment were available for occupation, when the agents of denudation 
and renewal were in active operation, and when a wave of rapid organic 
evolution was active. And a conjecture may be permitted that human 
evolution itself was probably hastened by the latest climatal severity 
through which the earth passed, the effects of which are only slowly 
passing away. 
