CLIMATES OF GEOLOGIC TIME.1 
By CHARLES SCHUCHERT. 
The ancient philosophers imagined that the earth arose out of 
darkness and chaos and that its present form and condition came 
about gradually through the creative acts of an omniscient and 
omnipotent God. Certain Greek philosophers tell us that the 
world had its origin in a primeval chaos; others that it arose out of 
water or an all-pervading primeval substance with inherent power 
of movement; that the energy of this primal matter determined heat 
and cold, and that the stars originated from fire and air. It was 
Empedocles (492-432 B. C.) who first told us that the interior of 
the earth was hot and composed of molten material, an opinion he 
formulated after seeing the volcanic activity of the Sicilian Mount 
Etna, in whose crater he is said to have met his fate. 
The geology of ‘to-day still teaches that the interior of the earth 
is very hot, but that the material of which it consists is as dense 
and rigid as steel, and that little of the interior high temperatures 
attains the earth’s surface because of the low conductivity of the rocky 
and far less dense outer shell. The older geologists believed that 
this shell originally was thin, and that therefore much heat was radi- 
ated into space, this idea being a natural result of the Laplacian 
theory of earth origin. In other words, they held that the earth 
was once a very small star which in the course of the eons gradually 
cooled and formed a crust. Therefore it was postulated that, because 
the crust formerly must have been thin, life began in hot waters 
and the climates of the geologic past were hot, with dense atmos- 
pheres charged with far more carbonic acid and water vapor than 
they now hold. The present type of climate with zonal belts of 
decidedly varying temperature and polar ice caps was thought to 
be of very recent origin, resultant from a much thickened rocky 
crust. All of these conceptions are now greatly modified by the 
planetesimal hypothesis of Profs. Chamberlin and Moulton, which 
teaches of an earth accreting around a primordial cold nucleus 
through the infalling of small cold bodies, the planetesimals, all of 
1 Reprinted by permission, after revision by the author. The article first appeared as chapter 21 in The 
Climatic Factor, by Ellsworth Huntington, 1914, pp. 265-289. Published by the Carnegie Institution of 
Washington, as publication No. 192. 
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