Go to National Library of New Zealand Te Puna Mātauranga o Aotearoa
Volume 15, 1882
Previous Article | Table of Contents | Next Article
– 516 –

Geological Survey.

During the past year Mr. Cox has been engaged for three months, from January to March, in an examination of Cape Colville Peninsula, more especially at the mining centres of the Thames, Coromandel, Waitekauri, Owharoa, Waihi, and Te Aroha. The most important results which he has obtained, lie in his determination of the stratification of the rocks at the Thames. He has shown there that the beds of the auriferous series consist of alternations of a moderately hard, compact, pyritous, tufaceous sandstone (tufanite of Dr. Hector); with less pyritous beds; a similar rock, which is, however, much broken up into pieces by joints; and a hard green dioritic rock, which is of true fragmental origin, but which passes at places into crystalline bands which are never continuous for any great distance. It is in the first of these that the reef has proved most highly auriferous, and while gold does occur in them while passing through the second class of country, they are not as a rule payable, and where the reefs traverse the hard rocks, they are absolutely barren. He has shown that several of these hard belts occur, and that where they are met with in the lower levels of the mines, the gold is cut off by them, but that other belts of auriferous country occur below, in which reefs have been worked. His work generally tends to show that, so far from the Thames being worked out,

– 517 –

there are yet, in all probability, as rich auriferous belts of country at lower levels as have hitherto been worked near the surface, and that gold will be found to quite as great depths as it is practicable to work. Besides this, he has illustrated the structure and behaviour of the reefs by numerous sections, and has also prepared a plan and section of the Ohinemuri and Te Aroha Districts.

During part of April he was engaged in an examination of the Blue Mountains, on the northern side of the Shag Valley, with the special object of determining the position of the Blue Mountain limestones. These he has shown are interstratified with slate and sandstone of Lower Carboniferous age, which form the first range north of the Shag River, and are separated from the Te Anau series of Upper Devonian age, which form the next range by a large fault which traverses the country in a N. 65° W. magnetic direction, and has a downthrow to the S.E.

Mr. Cox has also made special reports on the Woodstock Gold Field and the Ross and Humphrey's Gully mining claims on the West Coast, and has examined the lignite deposits at Norsewood, which he reports to be of an inferior character.

During the latter part of November, and part of December, Mr. McKay was engaged in collecting moa bones at Motanau and examining the country between Motanau and the Cheviot Hills. During this work the principal result arrived at, from an economic point of view, was the discovery of an outcrop of hematite about six feet wide, associated with the Triassic rocks of the coast range near Motanau. An analysis shows that this ore is specially adapted for the manufacture of hematite paint. After this he was engaged in Museum work during the month of January, and during February and the early part of March he examined the antimony deposits of the Carrick Ranges in Otago and collected fossils from the coal strata of the Bannockburn. He reports that there are three lodes which are apparently convergent, the thickest of these being two feet at its widest part; an outcrop of antimony can be traced at places on the surface from Alexandra, at the Manuherikia Junction, to the hills west of the Nevis Bluff, on Kawarau River, a distance of over twelve miles. During April and May he was engaged, at the request of the Hon. the Minister of Mines, in making a typical collection of the rocks of the Reefton District in duplicate. One of these collections was deposited at Reefton as the nucleus of a museum. While thus engaged he made a detailed examination of the relations of the various beds and confirmed the views previously held concerning them. He also gained important information concerning the extent of the coal-bearing areas, proving their probable continuance, as a basin, across the Inangahua Valley, comparatively near the surface about Reefton, but at much deeper

– 518 –

levels towards the junction of the Inangahua and Buller Rivers. He also made a special report on an antimony lode at Reefton, showing that an outcrop had been found which was about eighteen inches thick, and the reef had been driven on for 150 feet from that point without antimony being found. Heavy lodes of antimony are, however, found in several of the auriferous claims from Rainy Creek to Boatman's, which, in all cases containing gold, are treated in the ordinary way for the extraction of this alone, all the antimony and probably much of the gold being thus sluiced away. An examination of the auriferous cements at the head of Lankey's Gully showed that tinstone undoubtedly occurred associated with these in small quantities, but bad weather prevented any attempt being made to trace this back to its parent rock. He visited Langdon's Reef, near Greymouth, and reports that the thickness of the reef, at present being worked, is about two feet nine inches, which, being less than it was at the outcrop, shows the lode to be of a bunchy character.

The outcrops of coal in Coal Creek, Greymouth, were also examined, and he reports that two seams of coal 6 feet and 10 feet in thickness respectively, occur in the lease, in which a considerable quantity can be worked level free. In the month of June Mr. McKay paid a visit to the Terawhiti reefs, and reports that the Albion claim possesses a reef of an average thickness of from 18 inches to 2 feet, which has been followed along its strike for a distance of 6 chains, and for a depth of 130 feet. Some assays of quartz from this claim have yielded over 3 ozs. of gold per ton, but the specimen brought by Mr. McKay gave nothing but traces of the precious metal.

Previous Article | Table of Contents | Next Article