762 TEC GHA MELE TRIETEN, 
region immediately to the south of it, and that possibly they are 
but secondary eddies generated by the action of the great fixed 
ones. As before noted, the migrant eddies swing concentrically 
about the north Atlantic depression. 
Location of present glaciationn—Coming closer home to the 
glacial problem, it is important to note that the two great areas 
of present arctic glaciation are intimately related to these two 
permanent cyclonic areas. The Alaskan and Greenland ice- 
fields not only lie within these areas of barometric depression, 
but are peculiarly related to them. It is, at first thought, 
not a little singular that, while the Alaskan ice-fields lie on the 
northeast border of the Pacific ‘‘low,’’ the ice-fields of Greenland 
lie in the northwest quarter of the north Atlantic “low;”’ that ts, 
the chief glaciations lie defween the centers of the two permanent 
cyclonic areas. The apparent anomaly of maximum ice accu- 
mulation in the northwest quarter of the Greenland “low” prob- 
ably finds its explanation in the following considerations : 
1. The maximum precipitation (which is normally found in 
the southeast quarter of a “low”’) and the maximum ice accumu- 
lation should not theoretically be coincident; for the ice accu- 
mulation is not a true measure of the precipitation, but merely a 
measure of that fart of precipitation which is frozen when it 
falls and survives melting and evaporation. Now in the north 
and west quarters a larger percentage of the precipitation is 
snow than in the south and east quarters, where the sum total of 
precipitation is greater. Moreover, the melting in the north 
and west quarters is obviously less than in the opposite quarters. 
The annual isotherms for the southeast quarter range from 35° 
up to 50° F., while those of the northwest quarter range from 
35° down too’ F. The ice-fields of Greenland and the lands 
west of it lie in the tract whose annual average is below 32° F. 
Iceland, whose precipitation is greater, but whose glaciation is 
less, lies between isothermals 35° to 40° F. 
2. The configuration of the water area which wraps about 
Greenland gives special snow-precipitating efficiency to the 
winds that swing about the depression on its north side and 
