TJic Evolution of Cli?nates. — Manson. 173 
latitudinal belts sensibly parallel with the equator, but modified 
by elevation and ocean currents; whereas the corresponding 
preglacial climates were independent of latitude, and existed 
during eras. 
By the trapping of solar heat a gradual rise in temperature 
was inaugurated at that period, when by the exhaustion of the 
earth heat left in the oceans, the enshrouding clouds were re- 
moved. Not until this removal do we find zones of life belting 
the earth. In these new zones of climate there are being de- 
veloped higher, nobler types of life, and with the birth of the 
seasons there was ushered in upon the earth that light which is 
developing psychozoic life. 
Analogies Afforded by the Planet Mars. 
The fact that Mars presents phenomena which indicate 
milder polar climates than exist upon the earth leads the en- 
quiring mind into correct lines in its endeavor to solve the ter- 
restrial problem: 
To zvhat conditions are the climatic developments which were 
inaugiirated at the cnlmination of the Ice age nozv tending? 
The mean distance from Mars to the sun is about one and 
one-half times the mean distance of the earth ; and its volume 
is about one-seventh that of the earth. Unlike the rest of the 
planets, its own and other satellites. Mars reflects an orange 
red light — an important factor in interpreting climatic condi- 
tions. Upon equal areas the heat and light received by Mars is 
less than one-half that received by the earth; it by no means 
follows that its climates are proportionally colder, for as is well 
known in the case of the earth, the actual amount of heat a 
planet receives is not the prime factor in its surface tempera- 
tures. There are other factors which bear an important part, 
and arguments omitting these are liable to be fallacious. It is 
the omission of such factors which has rendered the climatic 
conditions presumably prevalent upon Mars difficult of inter- 
pretation. 
As either pole of Mars emerges from its winter, a compara- 
tively large white area is observed to encircle it. This area 
generally reaches down to Lat. 84° or 82°, or 6° or 8° from the 
pole, although sometimes extending to Lat. 60° to 55°, or 
through an area having a diameter of from 60° to 70° ; this 
