DUST CARRIED OVER SEA.

Hauraki Plains Gazette, Volume XXXX, Issue 5370, 4 January 1929, Page 3

DUST CARRIED OVER SEA.

A REMARKABLE OCCURRENCE

100,000 TONS FROM AUSTRALIA.

A comprehensive report has been by the Department of Scientific and Industrial Research relative to the dust-storm which visited New Zqalandi during October. Such a dust storm, it is pointed 'out, is a very unu'spal occurrence, the last previous occasion when such a fall was observed, and recorded being on November 14, 190'2. The dust on that occasion, as in October’s storm, was shown conclusively to be of Aus,tralian origin. The; fall of last October was far. heavier and more wide-, spread than that of 1902. All samples, of the dust collected' and forwarded for analysis had in appearance the same yellowish red or, buff colour, which gave a distinctive colour to, tbq clouds. and to the surfaces on which the dust fell, when examined microscopically the largest particles were found to have a. diameter of 0.08 mm., but these were very exceptional and flaky. There were few particles larger than 0.04 mm. The minerals which could be distinguished were flakes of mica and abundant wejU-rounded grains of quartz, and a certain amount of organic matter, was also pres.ent. The chemical analysis of the dust of both falls gives much the same result. It is similar to the red clay found over a large area on thq bed bf the Southern Tasman Sea, it being supposed that the deposit is really composed of dust blown from the Australian Continent. Dr. P. Marshall estimates that October’s dust fell over an area of at least 10,000 square miles, t/hq total deposit being approximately 100,000 tons.

The Director of Meteorological Services, Dr. E. Kidspn, enters, into de--tail concerning the meteorological Conditions prevailing before and at the time of the dust stor,m, showing that conditions over, Australia were favourable for the raising to high altitudes of vast quantities of dust Which would be carried in the direction of N®jw Zealand'. The thunderstorms. experienced in the Dominion at the time of the storm, and which were in many cases exceptionally s - vere, Dr. Kids,on says wenej almost •certainly associated with the presence of dust in the atmosphere, the dust particles absorbing the, sun’s -heat and convection being prpduced on a large s,cale and up to high levels.,

Dr, Kidson estimates the total deposit over New Zealand at between 60,000 and 100,000 tons, one of the most striking features being the chocolate or pink snow which fell in Otago. “The remarkable feature of the phenomenon,” he states, “is .that the dust should have been so lung concentrated in the atmosphere after such, a long journey. Thq average distance travelled by the time New Zealand was reached must have.been at least 2000 miles. The speed probably varied between 60’ miles per hour.' The writer is of the opinion that South and Central Australia must haves upplied their, quota to the total dust 'content, in addition to. Queensland and Nqw South Wales, and that the high degree of saturation could only have been reached by the atmosphere receiving additional supplieg during the course of several days. The transport of dust over long distanc.es is frequently recorded, but such a striking instance as the present had not previously come under the writer’s notice.”