772 T. C. CHAMBERLIN 
inherent in an aged earth. If the traditional view that the 
primitive atmosphere constituted a vast store that has been grad- 
ually drawn upon throughout the ages in the formation of the 
coals and carbonates, and was their chief source, the atmosphere 
at the close of the Paleozoic era must still have been rich, deep 
and dense to a degree far surpassing the present atmospheric 
state, for vast deposits of coal and carbonates have since been 
made through its agency. One of the most conservative as well 
as most competent estimates of the consumption of carbonic acid 
since the Paleozoic era places it at 5000 times the present con- 
tent. To be conservative, let this be halved and halved again, 
and still the content of carbonic acid is 1250 times that of the 
present. This atmosphere was so different from that of the 
Pleistocene and present period as to render uncertain, if not 
inapplicable, all arguments founded upon the phenomena of the 
latter. The question of the constitution of the Paleozoic atmos- 
phere is, therefore, fundamental, because it affects the substratum 
of all arguments based on present or recent experience. Even 
with the above excessively reduced estimate, do we reach an 
atmospheric environment in which any known agency applicable 
to the case can be reasonably postulated as competent to cause 
general glaciation? In such an atmosphere, or in any atmos- 
phere greatly richer than the present in heat-absorbing and heat- 
retaining qualities, are there any sufficient grounds for seriously 
supposing that any of the putative causes of Pleistocene glacia- 
tion, whether topographic, geographic, latitudinal or astronomical, 
could produce such a glaciation as is recorded under the tropics 
of the far Orient. It is not a part of the purpose or the method 
of this paper to antagonize other hypotheses, but rather to invite 
their development into working codperation and competition 
with that herewith advanced; but a wholesome interaction of 
hypotheses will be best attained by eliminating wholly untena- 
ble grounds and by bringing all hypotheses within the limital 
conditions of competency. It is, therefore, no transgression of 
my purpose to urge the question whether all hypotheses are not 
required, for their own conservation, to accept so much of the 
