AURIFEROUS BEACHES ON THE WEST COAST (REPORT ON THE).

Appendix to the Journals of the House of Representatives, 1887 Session II, C-05

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Sess. 11.—1887. NEW ZEALAND.

AURIFEROUS BEACHES ON THE WEST COAST (REPORT ON THE).

Presented to both Houses of the General Assembly by Command of His Excellency.

THE AUEIFEEODS BEACHES ON THE WEST COAST, AND THEIE UTILISATION. The sea-beaches on the west coast of New Zealand present features somewhat unique in goldmining. Gold in immense quantities, intimately associated with magnetite—the '' black sand '' of the diggers —and other minerals, and the ordinary sea sand and shingle, has been found along a coastline of some four hundred miles. With the exception of some small beaches at Gold Bluff, near the mouth of the Klamath Eiver, on the coast of California, I am not aware of gold in quantity having been found under similar conditions. Various theories have been put forth as to the source from whence this gold has been derived, and to account for its presence in such quantities along such an extensive coast-line ; however, I think we have only to carefully note the geological and topographical features of the Middle Island as laid down by such authorities as Hector, Haast, Hutton, McKerrow, and others, and keep our eyes open, to arrive at a reasonable conclusion both as to its derivation and final distribution along our shores. Lying in close proximity to the sea, and following the trend of the coast, we find a belt of auriferous country extending from Cape Farewell to Martin's Bay. The western watershed of the great Southern Alps in cross-section shows an abrupt descent and short course to the sea. This mineral belt is cut into by all our large rivers and their innumerable tributary branches : these, acting in unison with the immense glaciers yet in existence on the Southern Alps, and the various atmospheric agencies, are carrying on the work of degradation and transportation with increasing energy. High up in the gorges of these Alpine regions can be heard the everlasting thunder of Nature's batteries, for ever at work pounding, crushing, grinding, and disintegrating the minerals that ultimately form the sand and shingle of our sea-beaches; and, in obedience to natural law, the work of attrition and transportation goes on with unvarying result. Age after age and year after year has this work been going on. The river having delivered its freight to the sea, a new set of forces come into play—viz., that of wave and tidal action. As a rule, the set of the sea inshore on the coast is north-east: this carries the sand and shingle slowly but surely along the coast, building up the various beaches ; occasionally a heavy northerly strips the beaches and carries the sand to sea and to the south-west; the wave-action and heavy drawback to be seen on most beaches still further reducing the particles of sand, shingle, and metal hence the fineness of beach gold. The black-sand leads on our beaches are due to a peculiar swinging motion of the tide the digger applies the same method when trying a prospect on his shovel—acting on the shingle and sand in motion, whereby the comparatively-light material is swept down with the drawback of the receding wave, and tho gold and associated minerals, owing to their greater specific gravity, are left behind in a thin layer on the slope of the beach; this layer may not be more than a quarter of an inch thick, or it may be from lft. to sft. Just so long as the swinging and sorting motion goes on so will the deposit increase, until a change in the tidal action takes place, when the sand so laid down may be covered up with layers of grey sand and shingle, often 10ft. and 15ft. in thickness, thereby forming what is known as beach-leads ; or the whole may be swept away by a single tide, leaving not a trace behind of either black sand or gold. That the gold found on the beaches is primarily brought down by the rivers on the coast is a fact proved and known to gold-buyers, the quality of the gold on the beaches corresponding with that of the rivers in their neighbourhood. Australia and North America, although great gold-producing countries, show no such auriferous beaches as there are in New Zealand; but this is entirely due to the different topographical features of the countries mentioned. In Australia the auriferous streams have been arrested and imprisoned in her great central plains, never reaching the present coast-line. In California the valley of the Sacramento (formerly an immense inland sea) has been the recipient of the

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golden treasures of the western slopes of the Sierra Nevadas and the coast range; whilst such rivers as the Colorado, the Arkansas, the Platte, and the Missouri, all draining auriferous country, have deposited their gold in the great central basin of the western plains ; whereas the mineral treasures of the west coast of New Zealand have been, and are being, swept down from their source with such force that no permanent lodgment can be effected until the sea disposes of them along our shores. To utilise this great source of wealth so that it may benefit both the individual and the State is the problem to be solved. Like all our goldfields, our beaches have passed through the usual experience—first, a great rush of eager diggers, with rich and quick returns from the surface and shallow workings; then came what may be called the California-pump era, also giving grand results. Then, as the water grew more troublesome, came the era of big races and water-wheels ; but, not being able to master the water with their then appliances, claims were reluctantly abandoned, and finally, as far as systematic working was concerned, the beaches were abandoned. Many of the men connected with these big undertakings are still on the coast, and, having implicit faith in the capabilities of the beaches, would gladly avail themselves of any assured method of getting at the gold left in their old workings. Bich runs of gold were found above as well as below water-level, and it was only by the former that the first diggers reaped such a rich harvest of gold ; but some of the richest runs found on the Five-mile and other beaches were too far under the water, and were never worked; consequently the gold is still there. A new departure is about to be made in connection with the reworking the beach leads, by the introduction of new and improved methods ; amongst others, of a machine known as the " Ball Dredger," introduced into New Zealand by Mr. E. Brooke Smith; and another known as "Perry's Hydraulic Sluicing Plant," now at work at Gabriel's Gully, Otago, both of which machines are capable of working under water, and raising great quantities of material at a rapid rate. The Ball dredger can work to advantage 25ft. below the level of the old workings, thereby reaching a depth unthought-of under the old system. From a long and intimate knowledge and study of beach deposits and workings on the coast, I have come to the conclusion that, with such machines as the Ball dredger and Perry's hydraulic sluice, more gold will be obtained (and at far less cost) than was taken by the first workers, even if only worked to the depth of the known runs of gold; but, beyond all this, I hope to be able to demonstrate that, at lower levels than has ever been reached on our beaches, runs of gold quite as rich as those already touched will be reached by the Ball dredger. And, in support of the position I have taken, I would point out that all along the West Coast we are confronted with evidence that cannot be gainsayed of this fact, that stability is far from being the normal condition of tha Island. In the first place, we have positive evidence of upheaval presented to us in the fossiliferous beds and the remains of raised black-sand beaches found at various points along the coast, notably so at Charleston and Brighton, south of the Buller; Darkies Terrace, north of the Grey ; the Waimea and Hauhau, north of Hokitika ; and Sardine Terrace, near Arnot's Point: all from 200 ft. to 500 ft. above present sea-level. Professor Hutton, F.G.S., writing on the " Causes of the former great Extension of Glaciers in New Zealand," argues that the glaciers that filled our valleys in former times were due to 'an elevation of the land some 3,000 ft. to 4,000 ft. above the present , levels. If this contention is borne out, then we have had a period of subsidence reaching down to the present day, during which our glaciers have shrunk in proportion to the rate of subsidence, leaving all along the coast immense moraines as proof of their presence and evidence of the work done by them in former times. Whether this subsidence has been the result of abrupt transitions or of gradual downward movement it is difficult to say. However, during comparatively recent times evidence points to a gradual sinking. In support of this I would instance the dip and disposition of the strata in Boss Flat, as shown in section of main shaft, Boss United Gold-mining Company (see "Handbook of Mines"). At 380 ft. we find the various layers resting on what is termed terrace-bottom. This terracebottom is simply marine matter buried up, and probably resting on other layers of stratified wash; but neither in this nor in the overlying 380 ft. of wash has a single marine shell or fossil been found. From the dip and regularity of the strata it would appear as if the subsidence had been gradual, and that the different layers had been superimposed on each other in keeping with the rate of subsidence. Again, at the workings on the Five-mile Beach a turf bottom was reached considerably under low-water mark, covered with 20ft. of sand and shingle. Noting the action of the sea on the coast-line south of the Mikonui, most of the bluffs and headlands are composed of the remains of terminal and the ends of lateral moraines. In places only small sections of the terminals are left standing, while the magnitude of the original mass is indicated by immense boulders or erratics a considerable distance out to sea, and awash at low water. The sea-face of all the bluffs shows a vertical section, due, I think, to the continued aggressive action of the sea, the result of gradual subsidence. Whether this alternate elevation and depression is uniform on both sides of the Island, or whether, as some think, an oscillatory movement is going on, the east coast rising in proportion to the rate of subsidence on the west coast, it is hard to determine. We might possibly get reliable data if the angle of incidence of the old beach leads were noted and compared with the angle of our present beaches. However, be that as it may, there is sufficient proof that a subsidence has taken place, and is still going on. This being granted, our beach deposits must correspond in depth with such subsidence, and, as the same everlasting agencies have been at work for untold ages, grinding and pounding the mineral matrices, and the same, if not greater, rivers have been bringing down and sorting this never-failing stream of ground-up material to the same restless sea, so the same sequence of black and grey sand, shingle, and boulders must have followed in regular succession the gradual subsidence of the land ; hence the likelihood of payable gold existing at lower levels.

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If the conclusions I have drawn from observed facts and reliable data are correct, it follows that, with improved appliances such as I have indicated, with four hundred miles of beaches to operate upon, the result cannot be otherwise than satisfactory. Satisfied as to the richness of the beaches, and being confident of the suitability of the Ball dredger for the purpose required, a strong company has been formed in Christchurch to work the old Five-mile Beach, where they have secured 200 acres. I understand a portion of the plant is being manufactured in the colony ; but the patented part will be sent out'from England within four months. From a financial point of view, the reworking of our beaches by such a machine as I have indicated should commend itself to co-operative bodies of miners as well as to capitalists, the capital required not being over £3,000 for a machine of 100-tons-per-hour capacity, and the prospective profits being very great. Although for years the beaches have been abandoned, my faith in their value has remained unshaken, knowing well that sooner or later the inventive genius of our age would furnish the means of getting at our buried treasures ; and now, having found the means, it remains for the miner and the capitalist to apply them to their own advantage and the general good of the colony. Jackson's Bay, 2nd August, 1887. D. Macfaklane, Warden.

{Approximate Coat of Paper.— Preparation, nil; printing (1,075 copies), £2 6s.]

Authority: Geobge Didsbuet, Government Printer, Wellington.—lBB7.

MAP TO ILLUSTRATE MR. D. MACFARLANE'S REPORT ON THE BEACHES OF THE WEST COASTS MIDDLE ISLAND. 1887.