G. F. Becker—Temperature and Glaciation. 175 
temperature of the surface waters is most raised above the 
temperature which they would possess were the water station- 
ary. The present position of such a line could probably be 
ascertained, but in the past and warmer stages of the earth’s 
istory, more intense radiation from the sun probably stimu- 
lated these currents to much greater activity, and a somewhat 
different distribution of land probably modified their courses. 
It is quite sufficient for the purposes of this paper to point out 
that the absolute maximum lines of glaciation cannot have lain 
in the tropics, and can scarcely be supposed to have been ° 
further removed from them than the arctic circles; in short, it 
1S most reasonable to suppose that the greatest development of - 
° to 70° of latitude. 
cussed have had an influence, and igh ae Sar grins 
able that the forma- 
than sufficient to account for all the facts inexplicable except 
48 results of glacial action. 
Office U.S, Geological Survey, 
San Francisco, May, 1883. : 
¥ 
‘ * It appears to me, I confess, that substantiation of this hypothesis would be 
¥ no means superfluous. 
