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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