630 DAVID WHITE 
almost co-ordinate with this atmospheric impoverishment were, in 
the judgment of the writer, the size and height of the glaciated land 
masses. . 
That there was a change in the composition of the atmosphere 
toward the close of the Carboniferous is now generally admitted. 
Whatever may have been the effect of the limestone deposition, it is 
certain that the carbon extracted from air and sea and stored away 
in the coals and bituminous shales of the Paleozoic Coal Measures 
was far greater in amount than that in any other similar series laid 
down during geological time. Abundant red beds and oxidation bear 
evidence of the concomitant high proportion of oxygen in the atmos- 
phere and of rapid evaporation. 
Great extent of southern lands.—Concerning the size of the land 
masses the testimony is hardly less clear. It has been shown that 
the conditions of land plant and land vertebrate distribution call for 
the extension of land surfaces in one continuous or in several nearly 
contiguous continents including large portions of India, Australia, 
New Zealand, South Africa, and southern South America. It is 
probable that this connection was accomplished through the medium 
of an Antarctic continent, of which Australia, South Africa and a part 
of South America were possibly but lobes. The surviving or ves- 
tigial areas preserved in India, Africa, and South America bear 
evidence of the existence of enormous drainage surfaces on which 
the great seriest of conglomerates and coal measures of the Gond- 
wanas in India, the Dwyka and Ecca series in South Africa, and the 
Permo-Carboniferous of many states in Argentina and Brazil were 
laid down as fresh-water formations. The magnitude of the land 
ice’ action itself argues for extensive land surfaces in those regions. 
Problem of tropical glaciation—The most difficult feature of the 
problem relates to the geographical distribution of the glacial evi- 
dence. In India distinct ice work is found at 18° N.—1i. e., within 
the tropics—and bowlders regarded as glacial have been found at 
32° N., in the Salt Range. The Australian region within which 
glacial material is found extends from 20° 30’ S. to 42°S., and ranges 
t In South Africa 4,000 feet; about 10,000 feet in New South Wales; 1,200 feet 
of the Talchic conglomerate, while the Damuda series alone is said to measure 10,000 
feet in India. 
