3 
C.— 13. 
Gold-workings in cements of Cretaceous date are also likely to develop into considerable 
importance, and prove a comparatively permanent form of mining in both the Grey and Buller 
Valleys. In the Grey Valley, and on the south-west part of the Paparoa Range, the beds in 
question have been but little prospected with the direct purpose of proving them gold-bearing, but 
there lacks not indications of their auriferous character, both in the Mount Davy Range and in the 
Valley of Slaty Creek and Big River. In the first-mentioned part of the district a great develop- 
ment of coarse breccia-conglomerates and pebbly quartz-drifts extends through the range, from the 
slopes of the Grey Valley to the coast-line between the Nine-mile and the Twelve-mile Creeks, north 
of Greymouth. The coarser material of this division of the cements resembles the breccia-conglome- 
rates of the Horse Range and Trotter’s Creek that form the lower strata of the Shag Point Coal- 
field, in the Otago Provincial District, where, of somewhat finer grain and not quite so angular 
in character, it resembles the deposit of the Blue Spur, at Tuapeka. The finer and more quartzy 
material, which is the higher in the series, resembles closely the quartz-drifts of Central Otago, 
where, over a widely-extended area, they are often very rich in gold. 
In the Buller Watershed, along the east side of the Inangahua Valley, both kinds of deposit are 
developed ; the coarser brecciated material within the valley of Boatman’s Creek and the quartz 
drifts from Rainy Creek to the gorge of the Buller River, on the west slope of the Brunner Moun- 
tains. 
The vast formation of angular brecciated material represented in Hawk’s Crag, in the middle 
part of the Lower Buller Gorge, has not been proved to contain gold, but, so far as has been ascer- 
tained, no one has thought of testing any part of this formation with the object of proving it 
auriferous ; nor may it be said does it hold out any great prospects of rewarding efforts to show 
that it is payably auriferous, but there is quite a possibility of its being so. The arguments in 
favour of the Hawk’s Crag breccias being gold-bearing are, that the material, though angular, has 
been transported from a distance, and therefore some sort of arrangement favourable to the aggre- 
gation in particular horizons of the gold it contains must have taken place. The component rocks 
of the breccia material, though various, is mainly a subschistose rock, which, when in situ, was likely 
enough to contain gold-bearing reefs. Unfortunately, so far as proved, the gneissie schists of the 
Paparoa Range do not contain gold. 
While dealing with the probability of gold occurring in cements of Cretaceous date, I may close 
this by remarking that, during a recent visit to the Upper Buller Valley, in which I accompanied 
Mr. Gordon, Inspecting Engineer, we were both strongly impressed with the evidences that a very 
large part of the gold found in the valleys of the Maruia, Matakitaki, Mangles, &c., have been 
directly derived or liberated from conglomerates and pebble-beds under- and over-lying the principal 
oi' lower coal seams. The facts constituting the evidence on which our opinion as to the auriferous 
character of the conglomerates referred to have been known to all during the last twenty years or 
more, and in a vague way have been speculated upon by Mr. Cox when reporting on the geology of 
the district.* 
The facts are not more clear now than they have been at any time during the past twenty 
years ; but they are such as lead to the very definite conclusion that the conglomerates referred to 
are a great storehouse of gold, and are likely to prove of the utmost importance in the near future, 
now that attention has been pointedly drawn to them. 
Of course it remains to be proved whether the gold is widely dispersed throughout a great 
thickness of gravel or conglomerate cement, or whether it is concentrated so as to occur as rich 
deposits, allowing of its being mined from particular bands of conglomerate. From the well-rounded 
character of the bulk of the conglomerates the inference is that the gold will be found as rich 
deposits in particular horizons, although, at the same time, the cements may be generally gold- 
bearing to a less degree. I have, &c., 
The Under- Secretary of Mines, Wellington. Alex. McKay. 
GEOLOGY OF THE GREY AND BULLER VALLEYS. 
General Sketch. 
Grey Valley . — The principal source of the Grey River is Lake Christabel, which lies towards the 
south-western end of the Spencer Mountains. Towards the east, these mountains are formed of 
sandstone and indurated shales of probable Carboniferous age, followed at places by calcareous 
breccias, and diabasic ash-beds, red or green, that are probably of Triassic age. From beneath these, 
to the westward, appear mica-schists. 
From Lake Christabel the Grey flows west across the schist-belt till it receives the Brown Grey 
coming from the north, from the junction with which it has a south-west course between schist 
mountains on the east side of the valley and granite mountains on the west side, till, again alter- 
ing its course, the river breaks through the chain of granite mountains, and thus forms the first 
gorge of the Big Grey. Through the granite gorge the river at first runs north, then north-west to 
the point where it receives the Alexander coming from the north-east. Thence the Big Grey has a 
generally west-north-west course to its junction with the Little Grey, below which junction 
the united waters are known as the Grey River. The gorge of the Big Grey and the course of the 
Alexander River are in granite or gneissie rocks ; but around the sources of the Snowy River, a tribu- 
tary of the Little Grey, the granite gives place to unaltered rocks consisting of sandstones and slates, 
forming part of the auriferous series of Reefton (Maitai series of Carboniferous age). These rocks, 
as a belt four to five miles wide, extend north-east to the Inangahua, and from Merrijigs north to 
the reefing district of Crushington and Murray Creek. 
Geological Reports, 1883-84, p. 9. 
