304 
GEOLOGICAL CLIMATES 
minimum precipitation, but its heating or temperature effects were 
intercepted by clouds maintained by warm oceans and the avail¬ 
able supply of earth-heat inside the constant temperature chamber 
of moist air and clouds. Under these conditions the supply of 
water-vapor was dependent upon the stored heat of the oceans, 
and its disposition as a circulating agent in the form of vapor, 
clouds, rain and snow was fixed by solar radiation acting on the 
spheroid of air and clouds, these effects in no material way differ¬ 
ing from the present dispositions, except more uniformity in the 
exposed surface than at present offered by land and sea and 
variability in clouded areas. 
That upon the acquisition of a stable crust by the slow processes 
of cooling, and, by the overloading of continents at various 
periods with glacial ice, and the removal of these overloads under 
the effects of solar energy, the liberation of increments of heat 
ceased, and the oceans chilled to their point of maximum density. 
This degree is too low to generate sufficient water-vapor to main¬ 
tain continuous cloud density at any latitude, and leaves surface 
temperatures under the control of solar radiation. Under this 
control glaciation is not possible until this source of energy shall 
decline to an effectiveness less than that now reaching polar lati¬ 
tudes. That should this period arrive a type of glaciation not 
yet recorded would follow. 
Under the rewarming effects of solar energy temperatures 
must continue to rise until the surface of oceans shall rewarm 
to a degree which will increase evaporation therefrom and im¬ 
pose a check to further rise in temperatures by increased cloud 
extension and density. 
Within the field of speculative cosmology future glaciations 
of the earth are possible from two causes: (1) In the process of 
stellar evolution, at some remote eon of time, solar energy may 
decline to a maximum efficiency less than that now deglaciating 
polar latitudes and less than that now seasonally melting off the 
polar snow-caps of Mars. The ensuing glaciation would be unlike 
any yet recorded; it would be inaugurated in polar latitudes and 
it would be light, since cold and freezing oceans do not yield suf¬ 
ficient water-vapor for severe glaciations. (2) A cataclysmic 
rupture of the crust which would liberate sufficient earth-heat, 
now locked within its non-conducting crust, to rewarm the oceans. 
