The Guardian And Evening Star, with which is incorporated the West Coast Times. WEDNESDAY, AUGUST 23, 1933. GEOPHYSICAL PROSPECTING.

Hokitika Guardian, 23 August 1933, Page 4

The Guardian And Evening Star, with which is incorporated the West Coast Times. WEDNESDAY, AUGUST 23, 1933. GEOPHYSICAL PROSPECTING.

Geophysics -as applied to gold-mining is new in this country, but is well known abroad, particularly in Canada and South Africa.. When speaking on the matter recently in Otago, the Hon. E. A. Ransom, Minister in Charge of the Research Department, said; “It , must be emphasised that, while geophysical methods are distinctly useful in connection with gold mining, they do not locate gold, which is relatively always too small in bulk or concentration to be directly detected, but they assist in locating likely structures and /areas for prospecting, and it must he stressed that a geophysical report does not render prospecting unnecessary. I The work in any particular area takes time and the methods are not magical, yet, in many cases, the cost involved is well wortli while in comparison with the cost of prospecting bores, shafts, or tunnels, winch can be reduced in extent if reliable geophysical information is available.” Dr E. Marsden, the head of the Department, has fur- . ther explained that geophysical investigations of the Research Department have so far embraced (1) electrical; (2) magnetic; (3) seismic methods. At Cromwell all three methods have been applied experimentally and have yielded concordant results. Using these methods, old river channels eroded in the sandstone, have been traced for long distances, with a. depth of 70 to 160 feet. The information is of value in indicating where to seek prospecting shafts to obtain gold values, and to lay out development plans to the best advantage. The methods were applied also at St. Bathans and Cambrians, where many areas are overlain by conglomerates -already worked. -Geophysical investigation „ seems destined to be distinctly useful in gold-mining. It does not locate the gold, but assists in locating likely structures and areas for prospecting. The work takes time and the methods are not . held to be magical, but the cost involved is well worth while in comparison with the cost of prospecting bores, shafts or tunnels which can be reduced in extent if reliable geophysical information is /available. The appeal is a new one, but its scientific value is being well tested in the different countries. The result is improved mechanism for the different methods, which is being perfected as time goes on. The experience gained in regard to the different strata is also increasing the general knowledge as to estimating local situations. Naturally there are limitations, but these are being overcome steadily. It eliminates the gold “hit or miss” methods of blind stabbing, by defining at the outset the presence of ore bodies, though it cannot determine the quality or value of the ore, that being a matter for prospecting on the- information discovered. The method should prove of great assistance in prospecting on more economical lines. Efforts can be well directed from the outset, and in an auriferous belt the economical development can proceed to the best advantage. For a territory like Westland known to be so highly Umineralised, there should be great scope for investigation by the- new methods. There is a vast area of the country Crown Lands, and the -public estate might well be explored as to its mineral locations, and so form the basis for private enterprise to take up development schemes on the information supplied officially. The request for such an investigation on very complete and systematic lines should be pressed forward very wholeheartedly.