C—ll

2

In the same district, in response to an application made by Tayton and Jackson, of Nelson, an examination of an outcrop of chrome-ore, situated on the western slopes of Mount Starveall, at a height approaching 3,000 ft. above the level of the sea, was effected. The amount of ore observable, and the position of the outcrop, as described in the report which follows, are such that there seems little prospect of the ore being worked for some time to come, Considerable expense would have to be incurred in constructing a road or other means for bringing the ore to the low grounds in Aniseed Valley opposite the junction of the Serpentine River, whence it would have to be carted to Hope Railway-station. In the Collingwood District, Nelson, there was made an examination of the Aorere goldfield, with a view of determining its future value as a field for the development of hydraulic sluicing by ordinary methods, or by means of elevating machinery where the natural fall for the disposal of tailings would prove deficient. This work naturally led to a re-examination of several localities which have become historic in the discovery, progress, and decadence of this the first of the goldfields of the Middle Island of New Zealand. These localities included the Lower Parapara and the several areas held and being worked by the Parapara Hydraulic Sluicing and Gold-mining Company, which includes Glengyle Gully; the upper part of Appo's Creek and Appo's Flat; the northern part of Appo's Flat held by West, Adams, Fell, and Co.; the upper part of Lightband's Gully, the Golden Gully area, Blue Creek Plateau, and the Quartz Ranges. The general geology of the southern side of the Aorere Valley was worked out, and at all the localities mentioned the gold found in the more superficial drifts and gravels of the present creekchannels was regarded as having been derived from an older gravel- or drift-deposit, laid down at a time when the present physical features of the Aorere watershed had no existence. Former geological workers in this field have speculated variously as to the source of this older drift, and usually it has been credited to the action of the Aorere River within the bounds of the present watershed. Sir James Hector seems to be the only dissentient from this view, for he says, in the preface to the Geological reports for 1890-91, at page xii., "I have never felt altogether satisfied with the explanation that attributes the origin of the gold to the ordinary drift-gravels." But Sir James does not indicate clearly what the true origin of the gravels may have been. With less caution, perhaps warranted by a further array of facts and a greater depth and breadth of generalisation, there need be now no possible hesitation in pronouncing these beds as having resulted through the action of the sea, the gravels formed upon a sinking shore-line being successively submerged as the sea encroached upon the land. The date of the submergence was prior to the deposit of the marly and calcareous divisions of the Cretaceo-tertiary series of formations. The nature of the gravels is at places almost wholly quartz. It has been stated, in a previous report (on the older auriferous drifts of Central Otago, C.-4., page 38), that " there is no river in New Zealand at the present time that does or apparently can produce pure quartz-gravel by current action along its beds." And least of all might this be expected as a result of the action of the Aorere River now or in the past; the great number of tributary streams that throughout its course make junction with it, mingling with its more reduced gravels much angular and subangular material derived from a great variety of rocks in the neighbouring ranges. In schistose areas the action of the sea beating on the shore-line, by the pounding and carrying out to sea of the soft material, tends to the production of a residuum of pure quartz-gravel, the result being scarcely affected by small streams draining to the coast-line and bringing gravels from a region of schist or metamorphic rock. Away from the mouths of lesser and torrential rivers the cutting-back of a plane of denudation results in the production of a gravel the material of which is local, and thus distinguishable from those of a stream that has cut through a variety of rocks. Towards the north-east, in the Lower Parapara, Glenmutckin, and Glengyle, and to the Saddle at the source of Appo's Creek, the gravels of the older period referred to are somewhat of a mixed character; but this mingling of different material may have largely arisen subsequent to the laying - down of the original deposit, since it appears that both the older gravels and a more modern deposit due to the action of the Aorere River have been engulphed along a line of fracture that skirts the northern base of the mountains on the southern side of the Aorere watershed. But everywhere throughout this mingled deposit there are disjointed, or more or less continuous, patches of pure quartz-gravel, which are mainly the auriferous parts. In Lightband's Creek and Golden Gully quartz-drifts predominate, while at Blue Creek Plateau the quartz-drifts are mixed and alternate with coarser material which is locally derived. In the Quartz Ranges, the quartz residue of the harder gravel material of the original rocks forms deposits which occupy largely the north-eastern end of the auriferous area, and are to be followed along either the northern or southern border of the gravel-deposit to its south-western extremity; while the higher part generally, and at places the whole of the deposit, is composed of ordinary gravels locally derived. The local character of the coarser gravels on the Quartz Ranges have been noticed by other writers on the geology of the district, notably by Mr. J. Park, but he also failed to see in this an argument in favour of the marine or lacustrine origin of the deposit. As auriferous deposits of considerable extent, the various areas of these older gravels could be worked to profit, provided an ample or sufficient water-supply with the required hydraulic head, can be brought on to the ground at a reasonable cost. In the Lower Parapara area, as far as the supply from the Parapara River opposite the head of Lightband's Gully is sufficient, this has been done; the Parapara Hydraulic Sluicing and Gold-mining Company having a weir or dam in the river-channel, which lifts the water so as to pass the Saddle at the Old Richmond Hill Claim by a tunnel, and thence is conveyed across the Hit-or-Miss Saddle, at the head of Glengyle Gully, whence a pipe-line conveys the water across the Parapara and the intervening hills to the various points where it is required. These works have been in operation during the past twelve months; but, so far as can be gathered, only a moderate degree of success has resulted.