80 
organic matter and less CO2 set free; however this may be offset 
by the reduction in the amount of carbon locked up in the living 
organisms. These agencies, particularly the first three tend 
towards the acceleration of the refrigeration through the earlier 
stages but the process involved the conditions of its own arrest. 
BEGINNING OF THE REACTION. (1) The ice sheet itself 
was probably an important agency in checking the loss of CO2 as 
at its maximum it covered nearly 8,000,000 square miles, or 15 
per cent. of the land area. Perhaps another area at the border but 
outside of the ice sheet would be affected by prolonged freezing 
so as to check if not prohibit carbonation. 
(2) If the reaction once started the rising temperature 
would cause the release of more of the CO2 in the seawater and 
this would further hasten the process. 
(3) The increasing warmth would call forth more lime- 
secreting life forms in the sea which would hasten the process. 
(4) The increase of water from the melting ice would in- 
crease the shallow water zone. 
(5) The increased decay of organic matter would develop 
CO2. This may be offset by increased growth. 
(6) The increase of water vapor would increase the ther- 
mal capacity. 
INTERGLACIAL Epocus. If the land areas remained high 
and large nothwithstanding local depressions attributed to the 
weight of the ice the conditions would again prevail for a renewal 
of the glaciation. So glaciation and deglaciation might follow 
each other until the general causes disappear. That is in so far 
as the continental land masses settle back toward sea level or are 
worn away the conditions would disappear. 
INTERCURRENT AGENCIES. Glacial oscillations on the at- 
mospheric basis might be interrupted or disturbed by other out- 
side influences: (1) Any movement of the land which affected 
the aggregate atmospheric contact might disturb the rhythm. 
(2) Any notable change in the supply of CO2 by volcanic 
or other agency might affect it to a considerable extent. 
(3) The precession of the equinoxes has a rhythm of its 
