280 
The N.Z. Journal of Science and Technology. [Sept. 
capital expenditure, and where the labour problem is always a complicated 
one, we must look to our natural advantages for stimulating industries 
and increasing the wealth of the country. Gold-mining in New Zealand 
is at the present time in a depressed state, but hydro-electric power has 
been, and will continue to be, the means of enabling the mine-owner to 
handle bodies of low-grade ore which could not be treated at a profit with 
any other form of power. 
The chairman of the Waihi Gold-mining Company, in his speech at the 
annual meeting of the company held in May, 1916, stated, in reference to 
the Horahora hydro-electric plant, which supplies power to the company, 
“It is exercising a most beneficial influence on our costs in every way. 
So far as it can be estimated it is effecting a saving of between £20,000 and 
£25,000 per annum.” 
There seems no reason to doubt that the next few years will see large 
developments in connection with hydro-electric power in New Zealand, 
but as, in all probability, money will be dear, the whole question calls for 
most careful consideration from a financial point of view. 
Up to the present a large proportion of the hydro-electric plant imported 
has been of foreign manufacture. It is sincerely to be hoped that British 
manufacturers will in the future cater for this class of work, and more 
particularly for turbine and extra-high-tension gear. The comparatively 
small amount of water-power available in England, and the fact that very 
high voltages are not in use there, is no doubt responsible for the neglect 
on the part of the manufacturers in these two branches. 
MOUNTAINS. 
By C. A. Cotton, D.Sc., F.G.S., Victoria University College, Wellington. 
One-cycle, Two-cycle, and Multi-cycle Mountains. 
In the older classifications of mountains “ fold mountains ” figured pro¬ 
minently, while the term “ mountains of circumdenudation ” was generally 
reserved for residuals of high-standing plateaux of horizontally bedded 
rocks that had become deeply dissected by erosion. In a sense however, the 
ma ority of mountains, excluding young volcanic mountains but including 
those classed as “ fold mountains,” are mountains of circumdenudation. 
It has long been recognized that there is little, if any., correspondence 
between the fold-structures and the actual forms of mountains formed of 
folded rocks. 
If a mountain-range be uplifted by the compressive folding of which -we 
find evidence in the folded structure of the rocks, its initial form must be 
a huge pile of crowded, squeezed, and broken arches of rock. At a later 
time the limits of the range, though not its height, might be expected to 
correspond with the limits of the whole geanticline or composite arch; but 
no agreement need be looked for between the surface forms of individual 
arches and the details of the mountain-peaks. It is a commonplace that 
erosion is extremely rapid among mountain-peaks ; bare-rock surfaces 
abound, frost-action is vigorously at work, and steep slopes lead the broken 
waste downhill as talus, which is presently delivered into mountain torrents 
