GOLD MINING DEVELOPMENTS. 75 
derived from portions of the veins which were once above the present peneplain level 
(cf . pp. 12-14) and owes part of its concentration to the old streams which accomplished this 
planation and are now extinct. 
In the discussion of the tin placers it was shown.that as the surface of the land was 
gradually lowered by erosion from pre-Cambrian time to the present the heavy resistant 
minerals were left behind in such depressions as existed, constituting placer deposits. In 
the case of cassiterite the friability and solubility of the mineral probably allowed most of 
this accumulation to be carried away when the rate of degradation became very slow. 
With gold, on the other hand, its toughness, high specific gravity, and resistance to ordi- 
nary solvents allowed such amounts of it as had accumulated to remain. In other words, 
it seems probable that the placer deposits of this region represent concentration of the vein 
gold from that vast amount of material which has been eroded away since the veins were 
formed. The finer particles of gold have probably been carried away mechanically and the 
coarser grains have doubtless been slightly reduced in size by solution, but a large proportion 
of the content of the hard-rock deposits between the present and the original surfaces is 
probably now in the placers. This hypothesis would account for the comparative richness 
of the placers. The redistribution of streams on the revival of drainage after base-leveling 
explains the independence of present topography which some of the deposits show. 
MINING DEVELOPMENTS. 
GENERAL STATEMENT. 
Mining has been going on in this region for seventy-five years, and much work has 
been done. The effort has been expended at many places, however, and there are no 
extensive mines in the area. A few mines, nevertheless, by a comparatively small amount 
of development work, have opened up large ore bodies on which extensive open cuts or 
stopes have been made. The deepest working in the area is at the Hailc mine, where a 
winze extends 130 feet below the bottom or 350-foot level. The Kings Mountain mine is 
about 350 feet deep and the Colossus about 320 feet. Other mines having considerable 
workings are the Brewer and Blackmon, and it is said that there has been a relatively large 
amount of underground development at the West mine. 
METHODS OF MINING. 
The methods employed to obtain the ore from the deposits are varied in character. 
The placers were worked by panning, rocking, and sluicing; so far as known hydrau- 
licking has been practised in this area only at the old Tanyard placer at the Brewer 
mine. The same methods were applied to the decomposed upper portions of many 
of the deposits in place, sometimes in conjunction with crushing. When solid rock 
was encountered, development was carried on by means of shafts and levels. In general, 
the flat character of the country does not make tunnels advantageous. One has been 
driven at the Brewer mine, however. Vertical shafts are much more common than inclines, 
although numerous inclines were sunk on the veins or on the ore shoots in the early days. 
The interval between levels is usually small, but ranges from 30 to over 100 feet. 
In the largo replacement bodies the best ore was mined by stopes from underground 
workings. In the best practice levels turned from the shaft were run along the hanging 
wall of the ore body and at intervals raises were driven to the level above. The ore thus 
blocked out was broken by overhead stoping, pillars and level floors and roofs being left to 
hold the workings intact. When the levels were no longer needed, these pillars could be 
taken out. This method of mining was successfully employed for many years at the Haile 
mine by the manager, Capt. Adolph Thies. An ingenious means of driving the raises 
economically was put in practice at that mine and well deserves description. The steep 
dip of the ore body made it necessary either to drive steep raises or to drive them partly in 
barren ground. The latter was not feasible, and the former necessitated timbering for the 
