784 T. C. CHAMBERLIN 
if New Zealand were not connected with the Antarctic continent 
and South America, for the avenue of escape toward the Pacific 
would be circumscribed by the minimum elevations which the 
Gondwana phenomena seem to require. If the Antarctic-South- 
American connection were made, it would form a barrier to cir- 
cumpolar circulation, and all the polar ice-drift from South 
America to New Zealand would doubtless be forced northeast- 
erly into the Indian Ocean. This would certainly lend great 
intensity to the circulation of the polar currents through the 
Indian Ocean. The temperature of the latter would therefore be 
radically affected by the immense quantities of ice and cold 
water carried through it by this intensified circulation under the 
atmospheric conditions postulated. A like profound influence 
upon the overlying atmosphere must necessarily have followed. 
The narrow apex of the ocean under the tropics would probably 
have afforded little relief from the dominance of these currents. 
If this cold area be contrasted with the heated state which 
should naturally prevail in the Pacific Ocean, because of its vast 
breadth under the equator, its limitations at the north and its 
somewhat narrow communication at the south (particularly if it 
be shut off from the Antarctic flow past New Zealand) should 
give rise to antithetical conditions of temperature and pressure 
sufficient to radically influence the general circulation of the 
southern hemisphere. It is conceived that this extraordinary 
couplet might even introduce a systematic exchange of atmos- 
pheres between the northern and the southern hemispheres, con- 
sisting essentially of a cold north-seeking current flowing across 
the Indian Ocean into the northern hemisphere, correlated with 
a warm return current flowing from the northern to the southern 
hemisphere across the tropical regions of the Pacific, but this 
conception is not regarded as a vital part of the hypothesis. 
The configuration of the Atlantic is supposed to have caused 
it to play a subordinate part, the northern portion becoming an 
auxiliary of the Pacific and the southern portion more or less 
largely an auxiliary of the Indian Ocean. If we assume that the 
Gondwana extension connected New Zealand with the Antarctic 
