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a—9.

the same as that of the underlying blue shales. About 3 chains south of the Point—that is, on the side facing Tararu—they are curved, bent, and tilted up at high angles, and terminate very abruptly and steeply against the overlying volcanic breccias. At their base they possess a bluishgrey colour when seen in the solid, but they weather for a great depth to a yellowish-grey colour. They are highly pyritous, and occasionally interlaminated with thin layers of grit, consisting of small rounded particles of hard mudstone, mostly of uniform size. The blue shales also contain similar grit-bands, as well as nests and veins of pyrites. " The age of these old mudstones and slaty shales is still a matter of much doubt. Up to the present time they have yielded no distinct fossils, and the only remains that could be considered of organic origin are some small dark-blue tube-like markings in the lower blue shales, which may be referred to annelid or worm trails. These markings are, however, too obscure to fix the age of these rocks; and, until more satisfactory evidence is obtained, they may be regarded of Lower Secondary or Upper Palaeozoic age, most probably the latter. " Passing southward towards Tararu, at the point where the yellowish mudstones abruptly terminate, they are followed by a hard blue or bluish-green andesitic tuff or ash-rock, which abuts against and overrides them, resting both on the mudstones and shales. Where it rests on the blue slaty shales it contains small fragments of shale and masses of jasperoid quartz ; but, on the Tararu side, for the first 30 ft. from the mudstones, it is almost free from foreign matter. At the old quarry face, a few yards beyond this, it becomes quite brecciated with numerous angular fragments of blue shale, varying from J in. to \ in. in length, but in some layers the fragments are over 3 in. in diameter, and so abundant as to form a slaty breccia. " When solid and free from slaty particles, this tuff possesses a dark greyish-blue colour, and shows a finely crystalline structure, and might readily be mistaken for a solid lava. It decomposes rapidly when exposed to the influence of rain and other atmospheric agencies. It first assumes a greyish-green or purple colour, and soon become speckled with small, white, rounded particles, which apparently owe their origin to the decomposition and kaolinising of its felspars. It then passes into a fairly even or uniform yellowish-brown rock of moderate hardness, which in its turn gradually assumes a pale-grey or yellowish-grey colour, due to the abstraction of its iron oxides. In the latter state it is a very striking and instructive rock, and, to outward appearance, is similar to the ' kindly' gold-bearing rocks to be described hereafter. When it contains slaty particles, these stand out, black and undecomposed, in very marked contrast to the bleached and weathered tuff matrix. This slaty brecciated tuff, in all its different stages of decomposition, is well exposed in the quarry face a few chains north of Eocky Point. "On the beach near the mouth of Waiohanga Creek, on the smooth water-worn ledges at high-water mark, the tuffs, now free from slaty inclusions, are intersected by a number of small parallel mineral veins, many of which are filled with a greenish-grey material resembling the matrix of the enclosing rocks. The strike of these veins is north-east to south-west, and they are generally standing vertical. They vary from a mere thread to 6 in. in thickness, are often branching and faulted, and in many ways afford an excellent object-lesson in the structure and behaviour of lodes. A few chains further along the beach the tuffs are again similarly intersected by another system of parallel veins of pyritous quartz, while large veins and segregated masses of calcite are plentiful. The calcite veins often possess a comb structure, and in the centre the opposite and corresponding layers terminate in beautiful scalanohendrons. In some of these veins I have found bunches of galena and blende, associated with iron- and copper-pyrites. The assays of the galenas proved that they were poor in both gold and silver. "Between this point and Tararu Creek the tuffs pass imperceptibly into coarse breccias, consisting of irregular-shaped masses of greenish-grey andesite or tuff, enclosed in an andesitic matrix. In some places they contain large angular fragments of slaty shale, but these become rare as Tararu Creek is approached. From Eocky Point to Tararu the tuffs and breccias exhibit no distinct lines of stratification, and the southerly dip which they seem to possess is only indicated by the direction of the layers of the different materials. " Just before Tararu is reached, the coarse breccias are followed by a narrow belt of a greenishgrey compact tuff, or partially decomposed andesitic lava, containing a number of gold-bearing quartz-reefs, which pursue a general north-east course and traverse the City of Dunedin, Norfolk, and Sylvia mining leases in Tararu Valley. This is the lowest horizon of payable metalliferous veins in the Thames district. The metallic sulphides which accompany the gold are galena (often richly argentiferous), blende, copper, and iron-pyrites, while the principal oxides are those of manganese, which are often very abundant in the City of Dunedin and Norfolk Mines, especially in the shallower workings. "From Tararu to Kuranui Creek the rocks consist of greenish-grey and dark-green or purple breccias and tuffs, which up to the present time have not been found to contain a single payable reef. The same or similar breccias form the ranges on the south side of the Hape Creek, and in places they contain large masses of silicified wood, which would point to the existence of solfatara action during their formation. In the Kauaeranga Valley they are overlain by an enormous accumulation of trachytic tuffs and agglomerates, which are in many places intruded by dykes of trachyte and augite andesite. In the higher part of the river-valley the latter are well exposed in the narrow deep gorges, where they exhibit a beautiful columnar structure of huge hexagonal prisms. In all parts of the valley the tuffs contain veins and segregations of jasper, agate, chalcedony, as well as blocks of wood converted into wood-opal. At the foot of Table Mountain they contain intercalated beds of black and yellow coloured shales, and seams of impure brown coal. The presence of the latter proves the existence of a land surface in this area during the period of eruption of the trachytic tuffs and lavas. " Gold-bearing Formation. —At the Kuranui or Shotover Stream we pass on to the goldbearing formation of the Thames Goldfield, which extends without a break as far as Hape Creek on the south, and stretches in a north-easterly direction into the upper valleys of the Tararu, Puru,