HOBBS— THE FIXED GLACIAL ANTICYCLONE. 41 



cirri for its nourishment? " When will it first make its own weather 

 instead of taking- that which is brought to it by travelling whirls? 

 A partial answer seems to be aft'orded by two glaciers, the Vatna- 

 jokull of Iceland and the inland-ice of Northeast Land, Spitzbergen. 

 Some years ago Dr. Thoroddsen, who of all scientists was best ac- 

 quainted with the Vatnajokull, informed me that it possessed no 

 auto-circulation but appeared to be entirely dominated by the vigor- 

 ous cyclonic whirls which sunmier and winter are located over the 

 sea to the southwestward. This mass of ice is roughly elliptical in 

 shape with major and minor axes of about eighty and fifty miles 

 respectively and has an area of 8,500 square km. Subsequent ob- 

 servations by other observers lead me, however, to hold this as 

 perhaps doubtful. A larger ice mass which is more nearly circular 

 and with corresponding axes of one hundred and eighty miles is the 

 inland-ice over Northeast Land, Spitzbergen. The narrative of 

 Baron Nordenskiold, who crossed it in 1873, clearly reveals the 

 evidence of anticyclonic conditions. 



The great glacial antic3'clones of Greenland and the xA.ntarctic 

 can hardly be considered apart from their important role as parts 

 of the earth's planetary system of winds — they perform an important 

 service in turning backward toward the tropics those high level cur- 

 rents which have passed the horse latitudes and have not yet been 

 brought down to the surface, in doing which they remove the 

 moisture which had been locked up in the ice needles of the cirri. 

 They undoubtedly lend vigor to the entire circulatory system and 

 thus accentuate the climatic zones. When in the Pleistocene age far 

 greater continental glaciers lay over North America and Northern 

 Europe, the climatic zones must have been still more strongly 

 marked. There appears to be in this an explanation of the fact, 

 now generally recognized,'' that in the geologic past climatic barriers 

 have prevented the poleward or equatorvvard migrations of sensitive 

 organisms only during such geologic periods as were characterized 

 by extensive glaciation and presumably by correspondingly strong 



6 See F. H. Knowlton, " Evolution of Geologic Climate," Bull. Geol. 

 Soc. Am., Vol. 30, 1919, pp. 499-566. 



