306 
GEOLOGICAL CLIMATES 
which, having cooled more rapidly, have reached a more advanced 
stage, and present a surface of low albedo, utilize the violet end 
of the spectrum, and reflect deficient in this color. 
The first stage appears to be presented by the great planet 
Jupiter, which seems to be shrouded in dense clouds maintainevl 
by its own heat, and exposes a surface of high albedo 0.62, with 
banded zones and spots having varying tangential velocities and 
moving freely in its atmosphere. The heat emanating therefrom 
is about of that intensity which ^should be derived from reflected 
solar energy. The reflected light is normal and white, which shows 
that neither end of the spectrum is utilized or trapped to a greater 
extent than the other, as is the case with Earth and Mars. All 
the conditions are similar to those which a densely clouded earth 
would present to an observer in interplanetary space. 
Mars, on the other hand, presents a clear, or slightly cloudy, 
atmosphere, through which the features of the surface are faintly 
observed, notably the alternate formation and melting away of 
polar-snow caps as these are seasonally turned away from or 
toward the sun. The albedo is low, only .26, the violet end of 
the spectrum is manifestly utilized to a greater extent than the red 
end, and hence this latter color prevails in the reflecting light. 
Polar ice-caps are lacking, and in their stead polar snow-fields 
form in winter and melt off in summer, foreshadowing the con¬ 
ditions of the earth’s polar regions when energies and conditions 
now active shall be deglaciated, first the north polar regions in the 
land hemisphere and later'the ocean-bound regions of Antarctica. 
Three distinct stages of climatic evolution are therefore ap¬ 
parently presented by these three planets. Jupiter, in the stage 
through which the earth has passed; the Earth in the stage of the 
gradual development of solar controlled climates; Mars in a more 
advanced stage towards which our present developments are 
tending. 
If the eras of climates through which the earth has manifestly 
passed and the changes now passing before us have herein been 
referred to their proper principles, and correctly interpreted, the 
“intricate problems which have hitherto baffled the geologist” 
may prove grander by reason of their simplicity and unity. 
