i877-j 
Southern Hemisphere. 
347 
the flow of the ice itself, and the area of frozen precipitation 
being moved northward by the accretion on the northern 
slope of the ice-sheet ; for when it had attained a certain 
height above the sea-level it would intercept the whole of 
the moisture of currents of air travelling over it, and cause 
its precipitation on its northern slope, so that, as it advanced 
further from the Pole, there would be more and more preci- 
pitation, and its progress would only be ultimately checked 
by it reaching a warm enough latitude to greatly increase 
the liquefaction of the ice. The height of the ridge would 
increase as it reached more temperate regions, as it would 
primarily depend upon the altitude to which the moisture 
was carried before it was precipitated, and this would 
be greater the lower the latitude the ridge of ice at- 
tained to. 
I do not suppose that this ridge of ice, or the zone of 
greatest frozen precipitation, ever reached to New Zealand 
or to the Rio Plata, but only that the ice flowing from it did 
so. The zone of greatest precipitation may have been 
hundreds of miles farther south, and if anyone then could 
have stood on the edge of the great ice-sheet he would have 
seen to the south probably what appeared a level plain of 
ice reaching to the horizon, so gradual would have been its 
rise in that direction. M. Favre, in his elaborate account 
of the old glaciers of the northern rivers of the Alps, has 
proved that at their greatest extent the slope of the upper 
surface of the ice was very small, and for great distances 
nearly horizontal.* And Mr. Helland, describing the great 
ice-sheet that covers North Greenland, states that it resem- 
bles a great sea, but seems to rise slowly inland. Where the 
glaciers are largest on the coast the rainfall is not consider- 
able, and Mr. Helland concludes from this that the source 
of the ice must be far in the interior. f In consequence of 
this property of flowing with a small slope the ice has been 
conveyed to the coast for more than a hundred miles, at 
least, from where it was accumulated, and the whole of the 
lower part of its course is far below the limits of perpetual 
snow. The coast of Greenland does not, therefore, owe its 
icy mantle to the climate there, but to the outflow from the 
snow-gathering grounds of the far interior. And in the 
Glacial period the neighbourhood of Lyons was glaciated 
by ice that had flowed from the far distant Alps, and which 
in a great part of its course was nearly horizontal on its 
upper surface. 
* Archives des Sciences de la Bibliotheque Universelle, 1876, t. lvii, 
t Quart. Journ. Geol. Soc., vol. xxxiii., p. 146. 
