LOOKING FOR COPPER

Sun (Auckland), Volume 1, Issue 9, 1 April 1927, Page 3

LOOKING FOR COPPER

NEW USE FOR AEROPLANES PROSPECTING IN AFRICA The romantic day of the old “sourdough” prospector is rapidly passing. Scientifically-trained geologists are going into the field for large mining companies. And now airplanes are to be employed over a vast area in Africa to prospect for copper ore. While the country in the region to be searched—the new Katanga copper belt of the southern Belgian Congo and northern Rhodesia —is wooded as a whole, all of the many great outcrops of copper ore thus far found there by ordinary methods are almost wholly bare of vegetation. Therefore, the flying prospector will simply look for unwooded areas. The bareness of the copper areas is due to the presence of the salts of copper which kill the trees and other vegetation. In addition, in this particular locality, the structure of the rock formation causes the ore outcrops to lie in characteristic wide curves. This further narrows the search for copper. Working on foot the ordinary prospector was so close to the earth’s sur-

face that he cannot obtain a general view of it. To state a paradox, he “could not see the woods for the trees.” Such areas as those just described do not usually stand out in diagrammatic form to him. He needs a view of the earth’s surface from a distance. The airplane provides such a “bird’s-eye” view. “Cases can be cited,” it is said, “where there are two, three or more ore outcroppings in the same general locality that until recently were supposed to be as many different deposits; but familiarity with the district has brought to light a curved opening through the woods, from fifty to several hundred feet wide, connecting the croppings and proving them to be a single large deposit.” Similarly, many other outcroppings should become visible from far aloft. It has been found that an engineer and a practical prospector, assisted by a few natives, can prospect about 200 square miles in a year by the ordinary method. But an airplane can work about 1,300 times as fast as this. In actual work, the African area, which contains 130,000 square miles, js not merely to be scanned by the eye of the flying prospector. Instead, photographs of areas of about 1,000 square miles are to be taken by the continuous film method that is usually employed in airplane mapping. Wherever these preliminary photographs provide suspicion of the existence of ore bodies, the spot will be revisited and photographed more carefully. The geologist also will fly over it, studying it from the air. The next stage of advance will be land visits to these areas, and, if conditions then warrant, the pegging out of the claim and systematic prospecting by the usual system of cross-trenching aritt core drilling. It is not unlikely that the principle of this method, or some similar principle determined by local conditions, could be employed in other places. For example, airplanes have largely supplanted the old-time searcher for timber. This gentleman was often “personally conducted” on a devious route purposely chosen by the salesman, to take him through only the best timbered parts of a tract and thus to mislead him concerning its value. Airplanes are also being used for certain archeological investigations; it having been round, for example, that in England the lost outlines of prehistoric earthwork defences show plainly on the darker background of cultivated areas, while they could never have been recognised by those who stood only a few feet above the surface.