198 HOBBS— ROLE OF GLACIAL ANTICYCLONE [April 24, 



front — much the same conditions obtain, the wind blowing out to 

 sea with velocities sometimes as high as 40 m.p.s.^*^ 



Outward Sweeping of the Surface Snow which Falls Over 

 THE Central Areas of the Ice Domes, and its Accumula- 

 tion About Their Margins. 



The Centrifugal Snow Broom. — What may be characterized as 

 the centrifugal snow broom which sweeps out snow deposits from 

 the central areas and collects them upon and about the margins of 

 continental glaciers, is a necessary consequence of strong anti- 

 cyclonic conditions ; and its work is in evidence within all areas 

 where inland-ice has been extensively explored. 



From observations by Wegener, a wind velocity of 6-7 m.p.s. 

 raises the snow lying upon the ground and sets it in motion along 

 the surface at heights up to several decimeters (a foot or there- 

 abouts). With wind velocities of 10-15 m.p.s (22.4-33.6 miles per 

 hour) the migrating drift snow rises in a layer several meters in 

 height and interferes seriously with seeing conditions. With veloci- 

 ties of 20 m.p.s. (44.7 miles per hour), the snow is carried to a 

 height of 20 meters, or over sixty feet, and much higher in the lee 

 of obstructions in its path.^^ 



The Sweepings Below Outlets. — It is obvious that the results of 

 snow drifting by centrifugal surface currents above inland-ice will 

 be different according as the ice mass has been built up within a 

 rampart of mountains (South Victoria Land and the greater part 

 of Greenland), or as it has been allowed to shape itself independent 

 of such retaining walls. In the former case the drift snow pours 

 out along the courses of the outlet glaciers to form characteristic 

 aprons at their bases,^® or perhaps to produce definite fringing gla- 



1*5 " Deutsche Antarktische Expedition, Bericht iiber die Tatigkeit nach 

 Verlassen von Siidgeorgien," Zeitsch. d. Gesellsch. f. Erdkunde z. Berlin, 

 1913, p. 15; see also, Kon. preuss. Meteorol. Institute, Abh., Bd. 4, Heft II., 

 p. 9. 



i'^ Med. om Gronland, Vol. 42, p. 345. 



^•5 In the light of observations by Scott, Shackleton and David in South 

 Victoria Land, it seems probable that these apron-like snow deposits in the 

 form of dry deltas are due largely if not wholly to this cause. Not only 

 have explorers observed the rapid collection of the drift snow at the base of 

 the Beardmore outlet, but this origin is probable for the reason that accord- 



