a—3

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fossiliferous clay-mark of Miocene-tertiary age that are so largely developed in the flat country on the West Coast. This silt deposit marks the transition from marine to fluviatile deposits in the district, or, in other words, the passage from Miocene to Pliocene formations. The gravels (b) which belong to these passage-beds were the first-formed river-beds on the coast, and are generally the richest, though the gold is hardly, if at all, sorted out in these gravels in the form of defined leads. This gravel is easily sluiced away, as the pebbles are of moderate and about equal size, and are, moreover, rotten and decomposed, so that their surface washes away and all the gold is set free. In ordinary gravels, as miners are well aware, the pebbles are hard, and the gold is set in a dense ferruginous cement that adheres with great strength to the surface of the stones. On the top of the terrace is (c) the newer gravel, of very heterogenous materials, being, in fact, a morainic deposit formed by glaciers that in late Pleistocene times descended from the Alps and spread over the plains and river-beds of the earlier period. This deposit (c) contains huge blocks of stone mixed with sand and fine gravel. The two deposits, b and c, are the chief repositories of gold on the West Coast, but c is not so uniformly auriferous as b ; d is the ordinary flanking deposits of the existing valleys, and is auriferous or not just according to whether the river is traversing the older gravels in the upper part of its course. " ' Now, as to the richness of these gravels, b and c. They have been tested in various ways— (1) by surface-workings at various points ; (2) by tunnels driven through the hill in various directions ; and (3) by sluicing the faces of the terraces. I made about twenty trials in the first way from various points, and never failed to get a few specks of gold to each dish. The average from the middle of the deposit b gave ten specks to the dish of stuff, or about 151b. weight. These specks averaged 0-095 of a grain each ; and, as the stuff averages a specific gravity of 2-7, this would give the value per load (equal to 1 cubic yard) of ldwt. 4gr. for each speck present, or for my trials, lldwt. 20gr., equal to £2 6s. per load. The layer near the junction of the deposits b and c in like manner gave £1 Is. 6d. per load on the average, and the deposit c gave an average of £2 14s. per load. These results are very remarkable, but Ido not see how they can be erroneous ; but, still, experience shows that when sluicing on a large scale is commenced, while much coarser gold is obtained 'than by prospecting, the total average falls short of what was anticipated. The tunnel works were purposely so put in as to follow the richest layers, so that there is no wonder that they make the stuff appear even richer than the pan-prospecting. " ' The third source of information is the best, and I understand that sluicing 500 loads of the gravel b gave about of gold, or about 10s. per load, which is probably about the real value of the stuff. Reducing the area to 100 acres, and the thickness to 100 yards on the average, the claim will contain 60,000,000 loads of stuff, and it is only the question of the cost of getting that remains to be considered. On this point Ido not think that any hitch is likely to occur. When the dam is finished it will have an area of 11 acres, and afford 55 heads for 24 hours, with a possible inflow in dry weather of 100 heads. A short tunnel (the undertaking of which was a mistake, as it caused delay) has only to be completed now, when 20 heads will be at once available for sluicing. Under the circumstances, 20 heads should sluice 16,000 loads per day; when, taking one speck of the smallest size (viz., 002 of a grain, valued at one-fifth of a farthing) to each load would give £12 10s. per day, or £3,750 per year of 300 working-days, which would be about half the interest at 10 per cent, on the capital already invested ; so that two specks would pay the interest, and, if it were an average-sized speck to the dish, which is a very moderate estimate from the trials I have seen and described above, the yield would be £800 to £1,500 per day, and taking the lowest of these figures the claim will contain at present £3,000,000, and at the above rate will be worked out in twelve years.' (Geological Eeports, 1883-84, pp. xxviii.-xxx.) "If the results obtained from the working of these gravels in Humphre3 7 's Gully Claim have not equalled what are indicated above, they have yet been of such a character as to show that with prudent expenditure and careful management the undertakings of the company should at least pay, even as things stand. No doubt there is this drawback, that out of the present earnings heavy interest has to be provided for what is, perhaps, a rather large amount of capital expended on preparatory works, &c, and a considerable sum also for keeping the works in repair and good order." These extracts all go to show that there is a large field in Westland containing auriferous drifts which, if worked systematically, could be made to give remunerative returns for capital invested. It must, however, be borne in mind that the ground is not rich, and certainly will not give the returns indicated in the extracts quoted. Neither could the quantity of ground be sluiced away with the number of sluice-heads as stated. In ordinary gravel-drifts of similar character to that of Humphrey's Gully, for every sluice-head of water used about 6 cubic yards per hour should be washed away, if a proper system of working is adopted. On this basis, if there were a constant supply of even 100 heads of water, it would mean that 600 cubic yards per hour could be dealt with; and by using the water continuously, which ought to be done, it would be 14,400 cubic yards per day, which, taking the value of the material at Igr. of gold per cubic yard, is equal to 30oz. gold, representing a value of £120 per day. The quantity of auriferous drifts in this locality is very great, and were there 200 sluice-heads of water brought on to the ground to command the whole range to Blue Spur, two generations would not see the ground worked out. It is, however, not a venture for a poor man to go into, as it requires considerable capital to bring water and open out the claims, and unless a large supply of water is insured, any undertaking will prove a failure, as it is nothing but the large quantity of material operated on that will make ventures of the character profitable investments. There is a large field on the west coast of the Middle Island for mining enterprises, and every encouragement should be afforded those who are prepared to embark a large capital in works of the description indicated.