DRIFT OF ICEBERGS.

Hawke's Bay Tribune, Volume II, Issue 116, 1 May 1912, Page 3

DRIFT OF ICEBERGS.

AURORA’S CRUISE

IMPORTANT RESULTS E?;PECT! ; .!>

The forthcoming cruisa of the Aurora is likelv to prove of irmver.se va.’ie seicntifioallv. Prolessor David, vLeu interviewed, went enthusiastically- into the whole matter. He expects gieal results, hut he will ret, as has stated, personally accompany the expedition. Among those on the i ‘-iv'. will bo Mr. Waite, oi the Canterbury Museum, Christchurch, and Captain J. K. Dai is, aho w ill take the soundings.

Simultaneously with the soundings and dredgings, observations v.iii be macle regarding ocean currents, t >nipers’tures at the surface and at a d'ptb, and. the drift of icebergs. At pr t this matter, of such importance for shipping, been little studied, with the exception of the work done by the late Government Astronomer ol New South Wales, Mr. It. C. Russell. Mr. Russell has shown on his excellent charts that at times icebergs hate been known actually to ground on the shores of the Chatham Islands, about but) miles oast from Christchurch. That is, lhev have been known to go northwards up to latitude almost id -ntical with Piet of Hobart. Instances are on record, but They are rare, of bergs hating bcm actually sighted a few miles to the south of Table Cape. This is very close to tinlatitude of Sydney. The direction ol the drift of bergs is more depend.mi on ocean currents than on surface winds. It will ho a mattor of interest, in connection with the recent abnormal loosening of borgs in the Arctic: s<-as and their southerly drift past Labracloi and New foundland, to ascertain whethei the northerly drift of tin? Antarctic bergs is this year more pronounced than usual. As far as our present knowledga of iceberg drift in the Southern Ocean extends, it would seem that the bergs, which are formed of land ice developed out of probably many hundreds of years of snowfall over the Antarctic. continent, are broken off from time from the sheer ice-cliffs bounding the Antarctic coast, and are at first drifted westwards by the strong easterly blizzards. The, latter, however, frequently blow slightly from the S of E. and this tends to push the bergs towards tho WNIV. A short distar.c: north of the Antarctic circle the bergs come under the control of the ” brave west winds ” or “ roaring forties.” As far as is known at present, a large number of these bergs are carried e-:~. by these winds and the currents which they general.', from the area of i ! ’<. Antarctic coast betwe?n Dr. Manson': headquarters and those of his second in command. Mr. Frank Wild, in the direction of Tasmania.

SOUTHERN OBSTACLE”.

The ascertained drift of bergs in the Southern Heitiisp’i 're is veil shown ol the ie? chart prepared by the British Admiralty. A study ot this chart mak*,'.s it clear that cast f e ns of bercs. after arriving at a point about 700 miles -011111 of AdekiiJj. loitunately inr Aus traiian shipping do not usually lym. uithin about 300 miles of the southern extremities of Tasmania and New Zealand, with the exception just mentioned of the bergs which took ground at the Chatham Islands. The secret of this forcing back of the bergs southwards no doubt lies in the direction of prevalent ocean currents between Tasmania and New Zealand.

The report of the Aurora on the limit: this year of iceberg drift should prove of considerable interest, and especialh will the observations as to the trend ol ocean currents in tlies? hrtitudes. Indeed, the observations of ocean currents would be much more important a: this time of the year than the limits o! iceberg-drift: tor. from the point of view •>f the. latl'r investigation, the s.'.t.-oi. in May is rather late

SUMMER BREAK-A\VAYs

Icebergs, of course, break away from the icecliff of the Antarctic continent during the summer months as the resuit »f blizzards or exceptionally high rides. .>r possinlv earthquake shocks. Thee ere thus launched mostly in December. January, and February, but. after that time the sea around the Antarctic coast beeo'tiiiig frozen orer. it is no long?: possible for-bergs to form that season. Icebergs launched about the time of January wou’d drift slowly first west bx north, then later east by north during the months of February and March. But by Ab.rjl and May most of them would have become br.oken up by storms, or completely melted away. They are frequently, howe.er. found far north at ’east as late in the rear as April, so that it will be of interest to ascertain where

tli - Ann:-a finds th? line of iceberg drift Miniated in May. Tin* scheme for the work of the Aurora has been arranged partly in the first instance by Dr. Maw son and by Professor Manon, <jf the University of Melbcnrne, Mr. C. Hedlev (Assi.-taut-Curator of the Australian Museum. Sydney). and Profissor David. The latter, however, will he unable to accompiinj> the party on account of his University duties.