CHAPTER XIV, 
TEMPERATURE AND ALTITUDES OF SNOW-FIELDS 
AND GLACIERS. 
Ar altitudes varying in different localities according to 
their latitudes, we reach a zone of perpetual—or, rather, 
as it should be called, perennial—snow. ‘The snow-fields 
beyond are known as névés, while the fringe of ice begirding 
their lower edge are known as glaciers. In Norway we 
find both in the higher-lying plateaux, the remains, it may 
be, of a far more extensive Arctic snow-field than that 
which now exists in polar regions, one which, with snow 
and ice, during what in geology is called the glacial period, 
covered extensively the whole of Europe. 
While it is the case that difference in soil and difference 
in atmospheric pressure at different altitudes in a moun- 
tainous country are not to be altogether ignored in con- 
sidering causes of the geographical distribution of plants, 
it is chiefly as an indication of temperature at which dif- 
ferent kinds of trees are found at different altitudes that 
it is deemed of importance by the student of forest science, 
In this connection the line of perpetual snow is supposed to 
supply him with a valuable indication of a temperature 
which never falls much below the freezing point, from 
which he learn much by ascertaining how near to this may 
different species of trees can grow and flourish. 
In Norway in the zones of the oak, and of the birch, and 
of the cultivated fields, the temperature is moderate. In the 
midland districts the cold is more severe; but there pine 
and fir forests of boundless extent rise on high stony 
ranges, intersected with plains and valleys of meadow and 
cultivated land, and dells where the willow and the alder 
vegetate in great luxuriance. ‘And here, writes one who 
