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The Little Grey has, from its source to its junction with the Big Grey, a south-west course. Its broad valley is filled with recent alluvial shingle from Squaretown to the junction with the Big Grey. These recent alluvial deposits are mainly confined to the low grounds of the middle part of the valley and its north-western side. On the south-east side the valley is filled with a vast accumulation of gravels of Pliocene age that are cut across by tributaries of the Little Grey, such as Slab-hut Creek, Antonio's Creek, Adamstown Creek, and Blackwater. These and the lesser streams falling into them have so cut down and sculptured the Pliocene gravels (usually known as " Old-man bottom") that they now form broken hilly country, full of deep narrow creek valleys. On the north side of the lower part of Big Biver these gravel hills for a time terminate, a,nd high level river-terraces, formed by the action of the Big Grey, take their place. Several streams rising in the Paparoa Bange join the Little Grey from the north-west. The largest of these, the Otututu, or " Bough Biver," falls into the Grey just below the junction of the Little Grey. After debouching from the granite mountains, among which it takes its rise, the Bough Biver has its course for five or six miles across an alluvial plain built up of material mainly derived from the mountains in which it takes its rise, and which is therefore due to its own action. Below the junction of the Little Grey with the Big Grey the united waters are denominated the Grey Biver, and the valley of this part of the watershed from the junction to the sea, the Grey Valley. The lower alluvial grounds of this part are from two to five miles wide. These lower lands are limited on the south-eastern side by a belt of broken hilly country, which, having a breadth of from seven to eight miles, extends from the southern bank of the Big Grey to the Arnold Flat, a distance of nineteen miles, and is continued to the south-west across the valley of Stillwater Creek to the water-divide leading into the New Biver basin. This belt of hilly country is broken through by the Ahaura and Arnold Bivers, and its whole breadth is traversed by Nelson Creek, the main source of which comes from Lake Hochstetter. Numerous smaller streams take their rise among these hills, and generally follow a north-west course to their junction with the Grey Biver. These hills are formed of Pliocene gravels ("Old-man bottom"), and are nearly in direct continuation of the same gravels on the south-east side of the Little Grey Valley. All the streams breaking through or taking their rise in them are gold-bearing, and in the beds of many of them the gravels have proved exceedingly rich in gold. South-east of this line of hills the country is of lower elevation, and broad shingle-terraces (due to action of the larger rivers, the Big Grey, the Arnold, &c.) extend from the south-eastern limits of these hills to the foot of the high mountains forming the outermost of the series of ranges that culminate in the main axis and water-parting between the east and west coasts of the island. On the northern side of the lower part of the Ahaura Biver there is an alluvial gravel plain due to the action of that river when running at a higher level. On to this plain Orwell Creek debouches, at a point about one-third of its total length from its source. The Ahaura runs in a deep channel, having on the south-western banks steep cliffs of gravel belonging to the " Old-man bottom." The lower part of its course is through a deep narrow gorge to the lower river plain of the Grey Valley, across which it has a short course to its junction with the main stream. The Arnold. Biver from Lake Brunner flows along a broad valley, the surface-gravels on its north-eastern side for about a mile back from the stream being due to tbe modern action of the river, a lesser breadth on the southern side being due to the same action. Beyond the broad alluvial tract of this part of the Grey Valley, or to the south-east, the granite belt extends from the gorge of the Big Grey to and across the Ahaura Biver, and thence to the neighbourhood of the Kopara, and beyond this along the south side of Lake Brunner into the watershed of the Teremakau and the Westland district. East of the granite-belt there is a broad rib of mica-schist, the true limits of which have not yet been ascertained, and beyond this the unaltered Palaeozoic rocks, forming the main chain and extending eastward into the Amuri district of Nelson. On the north-west side of the Grey Valley, between Slaty Biver and Blackball Creek, alluvial flats near the level of the river are confined to the lower parts of Slaty Biver and Moonlight Creek. Along the western bank of Slaty there is a considerable area of such land, now mostly occupied by farmers. In the lower Moonlight the area is less, and the low grounds along this stream, both above and below the junction of the Meg Biver, form a narrow strip on both banks. Elsewhere from Slaty to Blackball, and south-east of the slate range or coal rocks, " Old-man bottom " appears at the surface, unless it is covered by high-level creek gravels of younger date. In Blackball and Ford's Creeks there are no heavy bodies of gravel-deposit due to other action than that of the streams at present operating in the denudation of the country. Between Blackball Creek and the Brunner Gorge, on this side of the valley, there is a fringe of shingle of limited breadth deposited by the Grey Biver, the mountain-creek wash found in the beds of the several streams of this part being derived from a narrow belt of slate on the slopes of the Mount Davy Bange, or from the conglomerates and breccia conglomerates at the base of the Cretaceous formation, as developed in this part of the Paparoa Chain. The Grey Valley below Brunnerton, as far as the Limestone Bange running from Point Elizabeth to Marsden on the New Biver, shows an alluvial triangular flat on each bank of the river. That on the northern side extending some distance up Coal Creek, that on the southern side being bounded by hilly country lying towards the New Biver Watershed. Buller Valley. —The area of the Buller Valley here coming under consideration, in the upper valley embraces the watersheds of the Matakitaki and Maruia Bivers, both of which take their rise in the Spencer Mountains, and flow north in nearly parallel courses to their junctions with the Buller. From the Grey Valley a low depression leads by way of the Bog Saddle into the valley of the Maruia, opposite, or nearly opposite, the junction of the Alfred Biver. The Bog Saddle is a bushcovered plain, formed by the action of the Maruia Biver when this was an affluent of the Grey, and not, as now, of the Buller Biver. The diversion of the Maruia to its present course, and the lowering of its bed, has cut away the eastern margin of the old high level river-bed, and the erosion of