414 I. Р. Koch. 
snowfall is distributed in different localities and in different years 
ought, therefore, to constitute one of the principal reasons why we 
may expect to meet with divergences in the fjord ice areas from one 
year to another. 
At any time during the summer new ice may form on the water, 
but the duration of the new ice during the summer is a short one; 
it melts before the rays of the sun and in positive temperatures, or 
it is broken up on the first occasion by the fresh breeze. In the 
month of September the open water is covered by a more lasting 
sheet of ice; only wherever there is a current there are still openings 
in the ice, where belated aquatic birds assemble. In October the ice 
Fig. 99. Wind-swept ice on a lake. March. 
is so strong that one can travel on it with comparative safety. Now 
is the time for autumn journeys. 
From November to March is the time for snow drifts. A wind 
velocity of 5 to 6 metres is sufficient to call forth a slight drift of 
snow; with greater wind velocities the lower stratum of air, up to 
an altitude of 10 to 15 metres, is filled with drifting snow. The 
wind velocities which determine the drifting of the snow, as it were, 
only occur when the wind is in the west and northwest. The trans- 
port of the snow therefore in the main takes place from land and 
out across the fjords and the sea, and they are undoubtedly very 
considerable quantities of snow which in this manner are deposited 
on the ice. 
Out at sea the snow must be deposited fairly evenly over great 
stretches; this, on the other hand, is not the case on the fjords, 
