VIVROTAHESTS\OPICA USE, OF GLACTAL, PERIODS 583 
equivalent (the great factor); (0) the absorption of carbon 
dioxide in sea water; and (c) its consumption in forming organic 
matter. 
The first and greatest of these is definitely connected with 
extension and elevation of the land, and the second is largely a 
sequel to it, dependent upon the temperatures it induces, while 
the third does not usually codperate with these two, but father, 
to the extent of its limited competency, offsets them. 
2. The sources of temporary enrichment embrace: (a) the 
discharge of the second equivalent of carbon dioxide in the sea 
by life action (the great factor), and (4) by dissociation ; (c) the 
diffusion into the air of carbonic acid absorbed in the sea water 
due to higher temperature antagonized by reduced partial pres- 
sure, and (2) the freeing of carbonic acid both in the air and the 
ocean by the decomposition of organic matter. 
These sources of fluctuation are definitely correlated with the 
elevation and extension of the land, on the one hand, and the 
extension of the sea and the reduction of the land, on the other. 
During an extensive elevation of the land, silicates are converted 
into carbonates at an increased rate and the limestones and dolo- 
mites are dissolved and carried to the sea more rapidly, both 
processes involving an acceleration of the consumption of carbon 
dioxide. Correlated with this extension of the land is a reduc- 
tion of the sea area attended especially by a lessening of the 
area of the continental shelves which are the habitat of the chief 
lime-secreting life, while the area available for pelagic surface 
life is also lessened. Reduction in the lime-secreting life retards 
the incidental process of freeing carbonic acid and returning it 
to the atmosphere. The result is a reduction of temperature 
which in turn increases the ability of the ocean to absorb carbon 
dioxide and reduces the dissociation of the second equivalent of 
carbon dioxide, thus further reducing the returning process and 
increasing the capacity of the ocean to hold carbon dioxide not- 
withstanding the reduction of the partial pressure in the atmos- 
phere. The reciprocating processes are thus temporarily affected 
in opposite directions so as to conjoin their results. 
