Mat 27, 1910] 



SCIENCE 



827 



■winds at Cape Koyds were either north from 

 the sea or southerly from the plateau. On the 

 southern journey south-southeast winds pre- 

 dominated, occasionally veering a few points. 

 The direction was thus largely due to topo- 

 graphical conditions. At the farthest, 88° 

 23' S., the many sastrugi trended from the 

 south-southeast, and all blizzards were from 

 that direction. 



The record of the higher winds is most im- 

 portant. As Cape Eoyds is practically at the 

 base of volcanic Mt. Erebus, the constant 

 volcanic steam-cloud served as a gigantic wind- 

 vane which was usually in full view. It de- 

 veloped that there were three normal wind- 

 currents — ^the surface up to about 6,000 feet, 

 the middle-level thence to about 16,000 feet, 

 and the high-level above all. The direction 

 of the middle-level was definitely shown by the 

 many strongly marked sastrugi, from 11,000 

 to 12,000 feet, to blow from the west-south- 

 west. Occasional eruptions sent steam-clouds 

 upward from the crater of Erebus to a height 

 of twenty thousand feet, and these cloud- 

 streamers displayed clearly and persistently 

 high-level current from the northwest. Inter- 

 ruptions and reversals of the various upper 

 currents were noted in connection with violent 

 blizzards. The detailed observations should 

 throw much light on the atmospheric circula- 

 tion of the southern hemisphere. 



Precipitation. — This was entirely in the 

 form of snow, which usually falls during bliz- 

 zards. The annual amount at Cape Eoyds 

 equalled about 9.5 inches of rain. The buried 

 depot on the Great Barrier showed in six years 

 and four months about 45 inches of melted 

 water, or more than seven inches annually of 

 rain. 



Ice-caps and Glaciers. — Shackleton's jour- 

 ney furnished much information on the phys- 

 ical conditions attendant on the great Ice Age, 

 of which the only surviving examples of note 

 are Greenland and the continent of Antarctica 

 — the latter of enormously greater extent and 

 importance. 



While existing data justify the belief that 

 the ice-cap of Antarctica covers an area fifty 

 per cent, greater than the continent of Europe, 

 we now have positive evidence of an unbroken 



expanse of inland ice extending north and 

 south more than 1,100 statute miles in a right 

 line, from 72° 25' S., the magnetic pole of 

 Mawson, to 88° 23' S., the farthest of Shackle- 

 ton, and covering an arc east and west of fifty- 

 five degrees of longitude south of the 78th 

 parallel of latitude. 



Erratic blocks and other proofs indicate that 

 the thickness of the northern edge of the con- 

 tinental ice-cap near South Victoria Land 

 exceeded by some two thousand feet that of 

 the present wonderful inland ice. 



Of the ice of the south-polar plateau at an 

 elevation of 9,600 feet, Shackleton writes: 



I do not think that the land lies very far below 

 the ice-sheet, for the crevasses on the ridges sug- 

 gest that the sheet is moving over land at no 

 great depths. The descent, towards the glacier 

 proper, is by a series of terraces. 



Everywhere were evident signs of waning 

 glaciation. Erratic granitic blocks of enor- 

 mous size were found on the flanks of Mt. 

 Erebus, while in 85° S., on the summit of 

 Mt. Hope, 3,350 feet above the sea and 2,000 

 feet above the surface of the adjacent glacier, 

 was strewn with erratic blocks. 



Murray believes that during the period of 

 recent maximum glaciation the ice-cap had a 

 thickness of four thousand feet in parts of 

 McMurdo Sound, now ice-free. 



It is thus evident that in the period of maxi- 

 mum glaciation there existed very extensive 

 oceanic ice-caps, which projected seaward far 

 beyond the continental shelf. Even in late 

 years these ice-caps were sufficiently projected 

 to furnish tabular icebergs or snowbergs of 

 enormous thickness and vast extent, though 

 they appear to have been more numerous from 

 fifty to eighty years since than to-day. The 

 present detachments are yet enormous, and 

 Shackleton's southern party heard the noise 

 and felt the ice-vibrations attendant on the 

 breaking-away of the sea-front of the barrier 

 while fifty miles distant. 



Three examples of oceanic ice-caps, or bar- 

 riers, yet remain: Drygalski Barrier, 200 feet 

 elevation, fifty miles by twelve in surface, 

 which projects 30 miles seaward with three 

 fourths afloat; Nordenskiold Barrier, of fifty 

 feet elevation, twenty by five miles in surface. 



