a—9.

much of the same nature, hence the following classification which was adopted for the latter sub division applies equally well to the rocks of the Heaphy Subdivision. (1.) Ordovioian : The Aorere Series. (2.) Miocene: The Oamaru Series. (3.) Pleistocene and Recent: Beach-deposits and river-debris. (4.) Post Aorere: Igneous Rocks. (I.) The Aorert Series. The rocks of the Aorere Series constitute the oldest beds in the portion of the subdivision so far examined, ami. forming as they do the mountainous "old land " of the interior, cover by far the largest portion of the area. Towards the north west the\ are obscured by younger beds. The Aorere rocks consist of coarse- and fine-grained argillites and gran waokes, occasionally graphitic and sometimes extremely pyritic, with occasional bands of schist They are intruded and somewhat altered in places by igneous rocks of both acid and intermediate nature. In appearance the sedimentary rocks are usually light greenish grey, weathering rustx. Sometimes extremely fissile, with greasy slickensideil surfaces. They have a constant Dearly meri dional strike, and in general a steep westerly dip. Towards the east of the subdivision, however. the angle of dip lessens, and the beds become much warped, minor anticlines and synclines being of frequent occurrence. (2.) Oamaru Series. -The Miocene beds of the area have their maximum development in a belt of country fringing the coast line, and having an average width of about two miles. The\ also appear as isolated patches on the slopes of the "old land "to the east. The series is repre seiited by beds of quai'tzitic breccia and arkositic sandstones, with shales and small coal-seams, overlain by quartzose conglomerates, followed by arenaceous limestones and calcareous sandstones The calcari B beds forming the upper members of the series are confined entirely to the upland country flanking the coast, and bounded mi the south-east by the cuestas already described. Fast of these, exposed by the denudation of the upper beds, the lower members of the formation are developed in an irregular belt of country, averaging about half a mile in width, and forming the valley between the "old land" and the uplands. Shales, with small coal-seams and quartzitic breccias, are exposed in patches mi the hillsides still further east. The beds throughout have a nearly constant slight dip to the north west. Occasionally, however, local flexure, the effect of faulting, is encountered where the beds abut against the " old land." ('!.) Pleistocent and Recent. Deposits of Pleistocene and Kecont age are encountered along and near the coast-line and in the beds of all watercourses. They consist of beach sands and gravels and river-debris. Unconformably overlying the calcareous sandstones of the Oamaru Si ries. ami exposed as irregular shelves on the crests of escarpments along the coast-line (sometimes al an elevation of 200 ft. above sea level), beach boulders, gravels, and sands are to be observed. Remains of these beds are also to be found quite half a mile inland from the roast. The coarser constituents of these beds are of argillite. gran wacko, and qiiartE, Corresponding with the rocks of the "old land." The liner sands are often extremely rusty, sometimes almost black, and frequently yield line gold to the dish. It is probable that the line gold found in some of the smaller creeks is a row ash from these beds. In places the Kecent beach sands contain payable leads of gold, associated with black sand: while the gravels of some of the sf reams were in the early days highly auriferous. ( I.) Iyneons Bocks. —The igneous rocks of the part of the subdivision investigated are of acidic and intermediate type. Acidic rocks are confined to a single sill of felsite of an average width of 20ft., exposed in the headwaters of the Anatori Kiver and extending uninterruptedly in a meri dional direction for some miles. Its connection with a large granite mass lying to the south-xvest of the area examined is undoubted. The intermediate igneous rocks of the area appear in a dyke of diorite, about 20ft. in width, transverse to the strike of the ancient seilimeiitaries. which is also exposed in the headwaters of the Anatori River. Examination has been too restricted to deter mine the age of these inlrusives beyond the fact that they are definitely Post Amere. and probably Pre Tertiary. Economic Geology. The economic possibilities of the portion of the Heaphy Subdivision examined are, frmn a geological standpoint, confined lo the production of gold and the preparation of building stone, though the agricultural possibilities are of considerable import ance. The strip of country border ing the sea coast, and formed by the decay of the calcareous beds of the Oamaru Series, affords a line sandy soil capable of great possibilities for the agriculturist. A large area of this land is still available for settlement. Flax grows luxuriantly mi the low hills near the coast, while good timber is to he found in places on the hills further inland. Cold. In the early days, owing to the discoverj of rich gold-bearing alluvium in some of the stream beds, the district was the scene of a diggers' "rush." Later on, auriferous veins were found : but these. thourr)i occasionally carrying high values, were unfortunately of small extent The \-eins occur near the heads of Malone, Friday, and Independent creeks. In all eases the old workings were inaccessible, but our examination, which was thus necessarily confined to surface outcrops, showed that the veins are all bedded with the argillites and grauwackes of the Aorere Series, and in consequence have a north and smith strike. Near the head of Friday Creek some small bin. veins are exposed in shallow prospect ing I renches. One of these veins shows a little free gold, and it is possible prospecting operations were abandoned somewhat prematurely. A picked sample of ore from this yielded on assay the following results: — Gold ... ... ... ... ... ... Bdwt. 19 gr. per ton. Silver ... ... ... ... ... ... 1 dwt. 21 err. Value ... ... ... ... ... XI 15s. ."..1. 4—C. 9.

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