INFLUENCE OF LIMESTONE UPON THE ATMOSPHERE 615 
without interference would be the exhaustion of the carbonic 
acid of the atmosphere, and, incidentally, the lowering of the 
surface temperature through the withdrawal of the heat-con- 
serving influence of the carbon dioxide, the reduction of the 
moisture of the atmosphere through the decline of the tem- 
perature, the checking of the vegetal growth, and if the 
process were to proceed to its extreme, the destruction of 
vegetal life, and of animal life as well. There would also be 
concurrent diminution of the chemical disintegration of the 
rock because of the lessened supply of the disintegrating 
agency, carbon dioxide, and because of the reduction of the 
auxiliary agencies, warmth, moisture and vegetation. Theoret- 
ically, rock disaggregation by physical agencies might grow 
into relative preponderance over chemical disintegration, since 
it would be aided by the sharp oscillations of temperature which 
would follow the withdrawal of the equalizing blanket of carbon 
dioxide and aqueous vapor. In such a case the land detritus 
from crystalline areas would constitute arkose deposits which 
stand in genetic contradistinction to the limestones, mudstones, 
and sandstones, which are the result of chemical disintegration 
through the preponderant agencies of carbonic acid and water. 
Whether this is really the explanation of the arkose deposits 
that occur at certain geological horizons is not here seriously 
considered. The assumed procedure is simply carried to its 
logical extreme. Arkose deposits may certainly be made 
locally under present conditions. 
But the process cannot reasonably be supposed, under cur- 
rent conditions, to go to the ultimate extreme of destroying all 
life and subjecting the nude surface to mechanical disaggrega- 
tion; for the process is self-checking. With the reduction of 
the carbon dioxide in the air, the rate of consumption is decreased 
as just indicated. At the same time the ocean is being enriched 
by the calcium bicarbonate carried down by the land waters, and 
the conditions there rendered more favorable for the formation 
of limestone and, through it, for the freeing of the second 
equivalent of carbonic acid. Even if the rate of freeing this 
