C—9.

General Ueoloyy.

General Classification.- Th< following classification, based on the general lithological and gtratigraphical evidence, is tentatively submitted pending a microscopic and pala^ontological exaliiinat ion : — (1.) Ordovician : Aorere Series. (2.) Miocene: Oamaru Series. (3.J Pleistocene and Keeent : Beach and river deposits: talus slopes. (1. 1 Post Aorere : Igneous Bocks. (I.) Aorere Series. Rocks of the Aorere Series are confined within the ana so far examined to a narrow strip bordering ihe western and southern Hanks of Mount Stormy. They consist of argillites, more or less distinctly bedded, with a south easterly strike. They are generally schistose ami spotted, and occasionally brecciated, effects produced by the intrusive action of the adjacent igneoUB mass which now forms Mount Stormy. Il is probable that further outcrops of this series of rocks will be eiicou nleieil along the base of the Mount Radiant Range. (2.) Oamaru Series. The beds which constitute the foothills have been, on account of their stratigraphical relation with somewhat similar hods of known age north of the subdivision, tentatively considered as belonging to the Oamaru Series of Miocene age. The beds are in places highly fossiliferous. and a paheoiitological examination will remove all doubt as to age. The members of this formation are, in ascending order, calcareous mudstones, with a band of arenaceous limestone, followed by argillaceous sandstones with small coal seams and occasional beds of loosely consolidated quartz wash, said to be auriferous in places. The maximum thickness of the series within the subdivision is probably about 600 ft. The beds have as a rule a gentle dip towards the coast. Exceptions to this general slight dip prevail, however, round the foot of the mount ai lis, where faulting has caused nioiioclinal folding with the production of steep inclinations of the iiala. (.'ii Beach and River Deposits, Talus Slopes. Owing to (he low gradients of the streams and rivers for some miles from their mouths, the coarse material is deposited before reaching the i oast, and consequently sandy beaches prevail with mud Hats round the mouths of the watercourses. The Mood plains of the various streams, the occasional terraces flanking the course of the Little Wanganui Kiver. and the narrow coastal plain fringing Ihe present shoreline all show Keeent rocks. Talus slopes are common in the mountainous region. ( l.i Igneous Rocks. Intruding the beds of the Aorere Series and forming the main massif in the east of the subdivision, is a huge boss of granite overlain in places by unaltered Oamaru beds. In point of age it thus lies between Orilovieian and Miocene, bill it is impossible as yet to assign a definite age to its intrusion. Biot ite-granite of grey appearance is the prevailing rock in the western portion of the igneous mass, but bands of pegmatite with large niuscovites are not uncommon. Towards the east dark (Horitic locks are frequently inel with, and appeal to be the effects of segregation from an original granitic magma. The diorites are invariably of line texture, while the granites are generally of a porphyritic nature. The igneous meks are of prime importance owing to the cupriferous veins w Inch occur in them. Economic Geology. The economic possibilities of the subdivision may be tabulated with respect to their relative importance as follows: — (1.) Copper and molybdenum. (2.; Gold. (3.) Coal. (4.) Lime. (0.) Building stone. ( I.) Copper and Molijlidcnuin . Of greatest importance from an economic point of view are the Copper molybdenum veins of the subdivision. These are confined, as far as present examination has shown, to a belt of count ry I hi cc miles and a half long and a mile and a half in width, traversing the western portion of the granite boss in a north-iiorl h-easlei ly direction from the eastern slopes of Mount Radiant to near the summit of Mount Scarlett. Outcrops are said to exist still further 1,, the south, and subsequent examination may prove their continuance in a northerly direction. Reference to the sketch-map opposite will show the general disposition of the veins, and it will be noted that those mi the Mount Kadianl Range have in general a north-north-west strike, while those on the slopes of Mount Scarlett trend in a northeasterly direction. It is highly probable that many of these; outcrops will eventually prove t" be connected, thus forming continuous veinsvsteins. But little work has as yet been done upon them, and there is ample scope for the location of further outcrops by means of surface prospecting. The veins are sometimes very distinct, with both walls well defined : again, they may be somewhat irregular and greiscu like with indefinite walls, whilst yet again they may have the nature of a stockwork a reticulated mass of small irregular veins. The vein-material is in the first case usually quartz alone, generally white, though occasionally rusty, with splintery fracture. In the griesen like veins unaltered feldspar forms a part of the gangue mat tor. while in the stockwork formation the country lock also carries values. The metallifeious i stituents of greatest economic importance are the copper sulphides chalropyrite and born he, with their alteration-products melaoonite and malachite, while ooveUite, azurite, cuprite, and chalcocilo are occasionally lo I bserved. The various Copper minerals generally appear in streaks and bunches irregularly distributed in the vein-material. Not infrequently, however, the ohalcopyrite is finely disseminated throughout the gangue, and may occasionally he seen replacing the ferro-magnesian constituents of the country rock.

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