134 
ISLAND LIFE. 
[part i. 
were it a northerly extension of a lofty Antarctic continent ? 
We may be quite sure that glaciation would then be far more 
severe, and that an ice-sheet corresponding to that of Greenland 
might extend to beyond the parallel of 50° S. Lat. Even 
this is probably too low an estimate, for on the west coast of 
New Zealand in S. Lat. 43° 35' a glacier even now descends to 
within 705 feet of the sea-level; and if those islands were 
the northern extension of an Antarctic continent, we may 
be pretty sure that they would be nearly in the ice-covered 
condition of Greenland, although situated in the latitude of 
Marseilles. 
Conditions determining the 'presence or absence of perpetual 
Snow . — It is clear, then, that the vicinity of a sea or ocean to 
supply moisture, together with high land to serve as a con- 
denser of that moisture into snow, are the prime essentials of 
a great accumulation of ice ; and it is fully in accordance with 
this view that we find the most undoubted signs of extensive 
glaciation in the west of Europe and the east of North America, 
both washed by the Atlantic and both having abundance of high 
land to condense the moisture which it supplies. Without these 
conditions cold alone, however great, can produce no glacial 
epoch. This is strikingly shown by the fact, that in the very 
coldest portions of the two northern continents — Eastern Siberia 
and the north-western shores of Hudson’s Bay — there is no per- 
ennial covering of snow or ice whatever. No less remarkable 
is the coincidence of the districts of greatest glaciation with 
those of greatest rainfall at the present time. Looking at a 
rain-map of the British Isles, we see that the greatest area of 
excessive rainfall is the Highlands of Scotland, then follows 
the west of Ireland, Wales, and the north of England ; and 
these were glaciated pretty nearly in proportion to the area of 
country over which there is an abundant supply of moisture. 
So in Europe, the Alps and the Scandinavian mountains have 
excessive rainfall, and have been areas of excessive glaciation, 
while the Ural and Caucasian mountains, with less rain, never 
seem to have been proportionally glaciated. In North America 
the eastern coast has an abundant rainfall, and New England 
