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Brown series was determined by Professor Hutton on purely palseontological grounds, while the stratigraphical evidence of the distinctness of the Mount Brown beds from the Ototara series was obtained at Oamaru, not at the Waipara, as implied by Mr. Park. The limestones belonging to this series are on the south-east side of the Aorere Valley, first met with on the shores of Parapara Inlet, and there dipping beneath the marly clay of Miocene age they reach the water-level at the point where the road crosses the mud-flat. Here they are seen to be underlain by quartz-grits. Towards the south-west they gradually rise to higher levels, and a greater thickness of quartz-drift is seen interposed between the limestones and the felspathic slates and sandstones of Silurian age. Finally they pass out of the watershed of the Parapara River into that of Appo's Creek, and extend west into lower ground to within a short distance of the road from Collingwood to Appo's Flat. The limestones next appear between the lower part of Appo's Creek and the river, where the calcareous rock is seen resting on the felspathic slates. The limestones are again seen in the bed of the Aorere River near the mouth of Doctor's Creek, and show in the lower slopes of the hills on the north-west bank of the Aorere. They also form isolated hills standing above the level of the sloping tableland on both sides of the road leading from the low grounds to Bedstead Gully and Golden Gully, in which are caves Of such interest as to warrant the reserving of the limestone area from sale. At a lower level, along the left bank of the lower course of the Slate River, Mr. Park shows the presence of a narrow strip of limestone or calcareous rocks of this age. This I have not examined, and, seeing that I consider the valley of the Slate River due to erosion only, it is somewhat difficult to understand how limestones of this age could occupy the position indicated. A considerable area of these rocks occur on the Rocky River Plateau, and the same rocks are found on a small outlier at the south-west end of the Pine Ridge, and beds of this age are found along the middle part of the Aorere Valley, as described by Mr. Park. Vl.—Cretaceo-tertiary. (a.) Conglomerates and Quartz-drifts underlying Limestone on the Southern Side of the Aorere Valley, Parapara, &c. —These beds, as far as concerns this report, are, on account of their auriferous character, of considerable importance. They are first met with in the north-eastern part of the district, on the north-western shore of Parapara Inlet, and their line of outcrop can be followed thence along the shore of the inlet and the hill-slopes on the left bank of the Parapara River to the saddle leading west into a small tributary of Appo's Creek, which joins the main stream at the lower end of Appo's Flat. Appo's Flat proper, extending along the banks of the main creek, is nearly comprised within the freehold, lately that of F. West but now the property of the Parapara Hydraulic Sluicing and Mining Company. But an equal or greater extent of low ground extends towards the north and north-east along the course of the small tributary creek already mentioned. Appo's Creek leaves the lower end of the flat by passing through a narrow rocky gorge, and thus a low-lying basin is formed 40 to 50 acres in extent, surrounded on all sides by hills, rising from 200 ft. to 500 ft. above the level of the lower grounds. To the west and north the hills are formed of coarse Pliocene gravel-conglomerates ;to the north-east of marly clays of Miocene age ; and towards the south-east, south, and south-west of Silurian strata, mainly composed of felspathic sandstones and slates, with bands of quartzite and quartz. The eastern hills slope at a most abrupt angle to the west and north, and along their lower slopes outliers and outcrops of quartz-gravels are found. The outliers of quartz-drift rest on an irregular surface of the older rock, which usually appears in the small gullies between these patches of quartz-gravel. Mostly the drifts are shallow deposits, and sometimes have the appearance of having been liberated from contiguous outcrops of quartz, and are partly rounded by mere exposure to atmospheric influences. At other places it is perfectly evident that we have to do with remnants of a uniformly well-rounded quartz-drift, in which the boulders are sometimes 6in. to lOin. in diameter. To the north-east these outlying patches of quartz-drift reach higher and higher, till near the saddle they attain an elevation of fully 400 ft. above the sea, or higher than the saddle and the limestones on its northern side. At the foot of the western slopes of these hills the older slates and sandstones appear, but their junction-line with the younger strata dips suddenly, and they are overlain by quartz-drifts at places, but more commonly these are not seen at the surface owing to a covering of slope-deposit and creek-wash of mixed material. On the north-east, from the saddle to the low gravels of the flat, quartz-drifts are seen to underlie the limestone at places, but generally the coarse gravels of Pliocene date, which cap the hills of marly clay, and bound the flat to the north and west, by rolling down the slope have covered over the outcrop of the quartz-drifts. On the west side from the gorge, at the lower end of the flat, slate rocks appear along the foot of the hills to near where the road to Collingwood leaves the flat. On the south-west the flat is bounded by a narrow ridge of old rock, the slope of which towards the flat is very abrupt. Appo's Creek leaves its upper gorge a few chains above Mr. West's house on the south-west side of the flat, and it was here for a few chains along the creek and across the whole breadth of the flat the principal gold-workings were situated. Upwards, towards the south, the ground was shallow and the bed-rock slate. The workings, however, showed that the shallow ground on the slate bottom suddenly ceased, and downwards, towards the middle of the flat, the superficial wash rested on quartz-drift, itself gold-bearing. The junction between the older rock and the quartz-drift was followed to some depth, and far enough to show that the old rock dipped away at an angle of about 45°. This high dip of the junction-line was further shown by the sinking of two holes 3 chains further down the flat. One of these was sunk to a depth of 140 ft., and this, after passing through about 30ft. of surface-wash, for the remainder of the distance passed through quartz-drifts. It cannot now be ascertained with certainty whether this shaft reached through the quartz-drifts to the underlying rock. By some it is so reported, and a mass of broken limestone is said to have been encountered ; but this may be doubted, as there is no limestone associated with the felspathic slates and sandstones on the hills to the eastward or south-west of Appo's Flat.