GOLD DISCOVERY

Greymouth Evening Star, 4 December 1929, Page 12

GOLD DISCOVERY

WESTLAND PROSPECTS. The following article, dealing with the prospects of the gold industry in Westland, appeared in the Wellington “Post” on Monday, from the pen of Mr Arthur P. Harper: — ’ Not long ago the “Monthly Bulletin” of the National Bank of New York said “the gold mines of the world are not producing enough to supply the accustomed base, at the 'rate at which credit expansion has been going on in recent years.” This is undoubtedly true; therefore it is of paramount importance to the Empire that every avenue leading to the discovery of new gold should be thoroughly explored. If we examine our New Zealand activities, we find that the gold being now produced is mainly derived' from using modern methods on old ground, or new processes to enable poor country to be mined at a profit. That no rich new field has been discovered for many years is partly due to the fact that the old-time prospector is dying out, and as civilisation has advanced in the Dominion the younger generation seem to prefer the “flesh pots” of civilised life. - Again, it may be partly due to the fact that the more!easily, reached gold deposits have been worked out and that to discover new fields would necessitate expensive plant in place of the old pick, shovel, and “dish.”

In the early “nineties,” I did some alluvial digging in South Westland, and also, for two years prospected and explored several rivers from the low country right back to their sources with no encouraging results. But in studying the past geological history of this part of the Dominion, especially with regard to the glacial action, I and my mate, the late Charlie Douglas, 'came to certain conclusions, which, if correct, would probably open up a field of alluvial gold as rich as the early days of the Golden Coast. We were both amateur geologists, but we had the advantage of being the only men who had gone into that back country, some of which has not been visited since, and comparing our observations with the theories of geological experts here and elsewhere, -I still firmly believe that our conclusions were sound. It would take up too much space to speculate as to where the enormously rich alluvial gold, found in the rivers and on the beaches of the West Coast, came from, but there is no doubt as a general rule that, wherever it may have originated, most of the gold won from the Grey River down to Hunt’s beach was taken from morainic deposits left by the ice of the glacier • period. It is therefore necessary to examine the history, formation, and action of these glaciers in the past.

ANCIENT GLACIERS. Sir Julius Von Haast, Captain Hutton, and other geologists have fully described the formation and extent of these old ice fields, so I will only shortly outline the conditions in the Westland during the glacial period, when the whole central, plateau-like, high country was covered with an ice cap which sent huge streams of ice toward the sea which, judging by existing evidences, must have been two to three thousand feet thick where it reached the lower level. These ice streams after leaving the highlands formed a great ice field along the West Coast, extending from (at least) the Teremakau River with very few interruptions right down the coast, forming ice fields similar to the Great Ice Barrier in the Antarctic. Owing to the character of the coun try this ice field would be covered with heavy moraine “debris.” So far this picture of the West Coast in that period is, I believe, accepted by scientists generally. Charlie Douglas and I came to the conclusion, from certain facts, that New Zealand had gone through two separate and distinct glacier periods in which the ice reached its maximum as above? described, and that between these two periods the sea followed the retreating ice well inland. If this is correct, then it appeared to us that when the first period of maximum glaciation ended, the ice sheet diminished and deposited, as it retreated, its burden of moraine matter, but not in sufficient quantity to keep the sea from following the ice back into the hills and covering the moraines at the lower levels.

During this period a deposit of marine matter would be formed on the top of the glacial deposit. In passing, I may say that I put this theory of two periods before Dr Mackintosh Bell when Director of Geology, and he said it is quite reasonable. After a period of retreat the ice again advanced to its maximum extension, and again formed an ice sheet \along the coast, which, like its predecessor, also carried on immense amount of surface moraine. This was followed by a second period of retreat, the glaciers gradually receding into the valleys until they reached their present positions. Here again the retiring ice would drop its surface moraine as it receded, but this time the debris left by the glacier was sufficiently large in quantity to form dry land. These vast moraines can be seen to-day, now covered with bush, in the hills and terraces round Lakes Mahinapua, lanthe, Mapourika, and others, and in the country behind Hokitika, Arahura, to Kumara, and other localities. Whether the gold came down on the glaciers from auriferous dykes, which have been demolished by denudation, is a matter of theory—as far as I am aware no definite proof exists as to the source from which it came, but the fact reipains that the richest finds have been in the old mordinic forma tion left by these ancient glaciers. In deed, it is certain that all the morainic debris deposited by the ice carried gold in very large quantities—but more or less thinly distributed. Sub sequent fluvial action has sorted out the material, and caused the gold to collect in very rich quantities in certain localities, which have been worked and sometimes worked over again, with good results. This auriferous “dirt”«lies on what is known to the diggers as the “bottom,” which consists of marine clays and sands, containing gravel, and in some localities takes the form of a hard conglomerate cement-like bed Impervious to ordinary tools. This formation *is nonauriferous, and it has in practice always been considered the true bottom below which it is .useless to prospect.

AN UNTRIED FIELD. The question is whether the socalled “bottom” is not possibly a false bottom, and, if so, what thickness it Now, if the theory is correct that there were two periods of maximum ice extension with a long period of retreat intervening, then it seems reasonable to suppose that the first

great ice extension deposited a large accumulation of morainic matter, which was subsequently covered by the marine formation deposited when the sea followed the ice inland during retreat, and this in turn was later on again covered by another huge deposit of morane during the second period of maximum ice extension. Thus you have the present West Coast gold fields lying on a marine “formation',” which in turn was super-imposed on an earlier but similar deposit of moraine. In other words, it is really a false bottom and covers another auriferous layer probably richer than the top layer, which has produced such large quantities of gold. No data exists fol* estimating the thickness of this supposed false bottom. The deep levels at Ross are, I believe, sunk in slip country and do not settle this big question. What is required is the selection, by geologists, of one or two likely spots and then by diamond drilling to test the thickness of this marine layer or bottom and see what lies below it. The cost would not be prohibitive, and the discovery of rich auriferous “wash” at a deeper level would be of such national importance as to warrant the test of a theory, which Dr Mackintosh Bell, in his official reports admits to be a “sane idea.”