SEARCH FOR ORE

Greymouth Evening Star, 26 January 1929, Page 11

SEARCH FOR ORE

O SUCCESS OF NEW METHODS So encouraging have been the preliminary experiments in geophysical survey in Australia by electrical and gravi-metrical methods that a new research section is now being formed to investigate the possibility of seismic methods. Fresh apparatus has arrived from Britain, and the personnel of the section is now being chosen. Experiments in geophysical survey are being conducted under the auspices of the Commonwealth Government, with the object of ascertaining Australia’s mineral resources. A party of scientists was brought from England last year, under the leadership of Mr. Broughton Edge to conduct a two-years’ investigation into the merits of the systems used. The scheme was suggested by the Empire Marketing Board, which is sharing the cost with the Commonwealth Government. At present the two sections in existence are working separately in their search for possible fields of copper, iron and sulphide ores.

The electrical section will shortly go to Tasmania where work on the Zeehan, Read-Roseberry, and RennisonBell mining fields has been suggested. The gravimetrical section, which has been mapping the outer reaches of the brown coal fields in Victoria, will probably go to New South Wales. The work is being followed closely by the various State Departments of Mines, for when the survey party presents its final report this will act as a guide (for the State authorities as well as for ,private interests. State authorities

have suggested the various areas for investigation, and State experts are attached to the parties for experience. The visiting scientists are also training four Australians in the methods used, so that they will leave experts behind when they return home at the end of their engagement in 1930. The work is described as being very interesting from a scientific point of view, as it is based on new theories and has not yet been definitely proved. Valuable results are claimed for it in other countries particularly in Scandinavia where rich iron ore deposits have been discovered under glacier moraines, deposits of earth and' rock which had hitherto concealed the true nature of the ground beneath. In the electrical method of survey, two steel stakes are driven into the ground some distance apart, and alternating currents are passed from one to the other by means of a dynamo. The current passes through the earth in various “lines of force” and these are thrown out of their different courses

if ore deposits exist. Continuous trial enables the scientists to map out the area of the ore field, and then the geologist is called in to determine the nature of the ore. In the gravimetric method the effect created on gravity forces by ore deposits beneath the ground is measured mathematicalally by means of a torsion balance. The new seismic section will adopt a method of measuring concussion vibrations. A deposit of explosives will be placed in the centre of a circle of seismographs, which are more familiarly known as instruments for measuring earthquakes. When the explosive is fired off the seismographs, it is expected, will be able to indicate the amount of distortion of concussion vibrations caused by the presence or absence of ore.