92 Glaciers and Glacial Radiants — Clay-pole. 
the inhabited earth had no glacier-system and perhaps even no 
continental ice-sheet during the colder times of the ice-age. 
Doubtless this great flat between the Altai and the polar ocean 
was covered with snow and ice during the winter as now, but 
these most likely disappeared with the returning sun as they do 
at the present time. Or if the summer failed to melt the whole 
of the accumulation of the preceding winter, yet at any rate the 
reduction was so great that the mass never became sufficient to 
produce motion by its pressure. 
We have now taken up all the leading features of the glacia¬ 
tion of the northern hemisphere that concern the rival theories 
regarding its cause. It is evident that the views here advocated 
are much more in accord with the facts than either the extreme 
theory of a polar ice-cap or that of merely local glaciers. As 
above enunciated it differs from the latter inasmuch as it re¬ 
quires an ice-sheet of continental proportions in both the Old 
and the New Worlds. But it attributes the formation not to cold 
and snowfall over the whole region covered but mainly to the 
accumulation of neve on the high lands which thus acted as 
gathering-grounds and from which the ice radiated in all direc¬ 
tions, reinforced in some degree by local precipitation. It is 
more likely however that this latter contribution acted rather 
by protecting than by thickening the ice below it so that the 
summer sunshine, not probably then very intense, was com¬ 
pelled to expend a great part of its force in thawing the snow 
that fell during the preceding winter. In this indirect way 
local precipitation may have largely aided in lengthening out 
the existence and the extent of the continental ice. 
On the other hand these views differ from the opinions of 
extreme glacialists less in regard to the temperate than in re¬ 
gard to the frigid zone. The members of that school will have 
little difficulty in accepting all that has been said of the former 
region. But the divergence begins when the area to the north 
of the ice-radiants above described is considered. Instead of 
looking to this part of the earth as the great gathering-ground 
for all the glaciers and ice-sheets to the southward and as a re¬ 
sult seeing there, in imagination, a parent neve thousands of 
feet thick and even massive enough to affect the very centre of 
gravity of the earth we And no ground for the belief that there 
