632 DAVID WHITE 
its attending decrease of humidity, would result in a marked increase 
in the difference between the mean temperatures of land and sea, 
the loss of the sun’s heat by the land being greatly accelerated as 
compared to the lesser loss by the sea; so that despite stronger winds, 
convection currents, etc., an increasing cold would prevail in the 
greal land areas. If to this principle is added a most important fact, 
that altitudinal differences in temperature would be exaggerated if the 
carbon-oxide of the atmosphere were reduced, it will appear probable 
that partial depletion of the carbonic acid gas might produce greatly 
magnified effects of cold, with accentuated seasonal differences at 
relatively moderate elevations in the interiors of the land masses," 
while the climate near sea level especially in the smaller lands or in 
proximity to large oceanic bodies, might still be mild and relatively 
equable. It might thus be possible for the Cosmopolitan flora to 
survive on the low or base-leveled coasts of the sea-girted northern 
lands while glacial conditions prevailed at no great elevation in the 
interior plateaus and subaerial basins of the Southern “ Gondwana- 
land.’ The writer is therefore disposed to believe that the glacia- 
tion in the GANGAMOPTERIS province was secondarily due to the— 
elevation of its land masses to greatly reduced refrigerative altitudes 
at the time of the post-Carboniferous uplift. The elevation of the 
southern land masses and their erosion and glaciation are fully dem- 
onstrated. The enormous thickness of continental sediments already 
noted in Africa, India, and Australia, including over 1,200 feet of 
basal conglomerates alone, is itself evidence of a considerable height 
of land. In Australia there was probable oscillation and recurrence 
of glaciation as shown by the intercalation of the Greta coals and 
shales, the latter inclosing the pure GANGAMOPTERIS flora. 
t The accelerated decrease of temperature in ascending the atmospheric column 
occasioned by reduction of CO, is remarked by Chamberlin. Granting that carbonic 
acid gas in the atmosphere exerts the influence in arresting the outgoing heat rays 
attributed to it by Arrhenius and Chamberlin, it is plain that, on account of the exten- 
sion of its zone far above that of the humidity, an increase or reduction of its volume 
must also directly and strongly affect the differences in temperature due to differ- 
ences of altitude. With reference to the climatic effects of changes in the proportion 
of CO, in the atmosphere, the reader is referred to the most valuable discussion pub- 
lished by Professor Chamberlin in Vol. VII of the Journal of Geology, 1899, or the 
second volume of the Geology published (1906) by that author in collaboration with 
Professor R. D. Salisbury. 
