C—9.

A small amount of platinum occurs in the black-sands leads. This is rarely of sufficient importance in itself to render the sands workable, but is in places a very valuable by-product with the gold. Popular interest in the Orepuki black sands al the time of my visit centred around a heavy grey sand obtained in fairly large quantity in the concentrates. This was thought by many of the local miners to be platinum in a finely comminuted state ; but it has been found on microscopic examination to consist in the main of rutilc and ilmenitc (titaniferous magnetite), with a minor amount of quartz, fragmentary garnets, and other rock-forming minerals. The disc-shaped grains of platinum which sometimes occur sparingly in such sands are easily recognizable under the microscope, but none was found in the sample of sand examined. It is possible that a grain or two of monazite may be present. In a similar sample of Orepuki sand analysed in the Dominion Laboratory, however, the total amount of rare earths (other than zirconia) was less than 0-02 per cent. Rutile is a very hard mineral, and the crystals and grains in the sand are decidedly angular. If found in sufficient quantity, which in this case is rather unlikely, it would make a fairly good cutting and polishing material. West of the Waiau River, which enters the sea about nine miles west of Orepuki, and northward to Lake Te Anau. lies an unknown wilderness which is thought by the Orepuki miners to contain much mineral wealth. Ores of tin, manganese, and copper, together with coal, asbestos, and garnets, have been reported from this mountainous area. GEOLOGICAL RECONNAISSANCE OF THE MOKAU COUNTRY. Introduction. During the past few years much interest has been taken in the development of the petroleum industry throughout New Zealand. This has been chiefly due to the comparative success met with in the boreholes Nos. 1, 2, and 3 of the Taranaki Petroleum Company (Limited), operating at Moturoa, just out of New Plymouth. Among other parts of the country, men interested in the search for petroleum have turned their attention to the Mokau district. Here it was thought that, as suggested in former geological reports, the same strata as those carrying oil near Moturoa would lie much nearer the surface than in the neighbourhood of New Plymouth, and consequently drilling to pierce the supposed reservoirs of petroleum would not have to be carried to such great depths. It was with the intention of obtaining definite information as to the prospects of the Mokau country as a possible petroleum-field that a reconnaissance was made through this part of the Dominion by the writer. Owing to the very brief time available, the exploration was naturally a very hurried one, and was scarcely sufficient to settle the main question at stake. However, some interesting and valuable information on the locality was obtained. The reconnaissance lasted from the 3rd November —the day on which Waitara was left—to the 10th November, when Te Kuiti was reached. During that period a rough examination was made of the shore-line between Ureti and Tongaporutu, in the vincinity of the White Cliffs ; of the Mokau River to a point twenty-three miles, following the bends of the river, from the mouth ; of the shore-line from Mokau to Petone Creek, two miles north of Awakino Heads ; and of the main road between Awakino Heads and Te Kuiti, through Mahoenui, Paemako, and Piopio. Situation and Topography. The Mokau is a fine large stream which enters the sea about thirty-eight miles north-east of New Plymouth. It is navigable for small coastal steamers for twenty-two miles (by the river) from its mouth, and could, with some slight artificial excavation, be made available for boats still further up its course. The Awakino and Tongaporutu are smaller streams than the Mokau —the former entering the sea about three miles to the northward, and the latter about ten miles to the southward. Mahoenui, Paemako, and Piopio are unimportant post-offices in the heart of the King-country, and situated respectively twenty-three, fifteen, and twelve miles (air line) to the south-westward of Te Kuiti. The distance in a straight fine from Te Kuiti to Awakino is about thirty-eight miles, but the route taken by the writer is much longer. The whole country examined forms, physiographically considered, part of the Wanganui coastal plain —an area composed of marine strata but recently elevated (geologically speaking) above the sea. Thus the crests of the various ridges show, generally speaking, a gradually increasing elevation in going inland, and indicate the surface of the old plain. On the whole, the country —especially towards the coast or westward of the gorge of the Mangaotaki, a tributary of the Mokau—may be described as hilly, with narrow-crested ridges separating the numerous watercourses —the tributaries of the Awakino, Mokau, &c. Eastward of the Mangaotaki, particularly in the neighbourhood of Paemako and Piopio, the country is more rolling and undulating than hilly. The principal streams, the Mokau, Awakino, and Tongaporutu, flow at gentle gradient, and, though inconsiderable rapids occur in their courses, waterfalls of magnitude exist only in their headwaters. The Wairere Falls, on the Mokau, are situated near Paemako, or about twenty-five miles in a direct line from the sea. Below these falls the Mokau flows in a narrow deep valley, with precipices in places coming to the water's edge. Above the falls its valley is more open for some miles, but in its headwaters its course is broken by gorges. The Awakino and Tongaporutu resemble the Mokau in general character. The road from Awakino to Te Kuiti follows the low flood-plain of the Awakino for some three or four miles, and then rises and falls over hilly country as far as Mahoenui. Here it passes through a spacious flat carved by the Awakino and its tributary the Mangaorongo for about four or five miles ; then follows hilly country as far as the railway, save in the vicinity of the rolling plains around Paemako and Piopio. Terraces may be seen along the sea-shore in many places, marking old levels of the sea.

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