PROCEEDINGS OF SECTION C. 499 
sphere than would occur naturally in the fine cracks and fissures 
of a rock, where the action would be slower. Moreover, it is 
highly probable that, although we may be able to form many 
minerals artificially, both in the wet and dry way, still, similar 
minerals may not always be constructed by Nature according to 
our methods ; for natural solutions are so much weaker than those 
used in the laboratory, besides being impure, and time is no 
object ; so we cannot say for certain that such and such a 
reaction took place among the many possible combinations, 
although we may be aware of the final result. 
I further consider that lines of weakness having been determined 
along legs of the anticlinal and synclinal folds, a.tortional strain 
caused a gradual displacement for a few feet, giving mineral 
solutions an opportunity to deposit their burden between the 
fractured particles of rock. The tortional strain that caused this 
movement culminated in a crack, which was filled with diabase ; 
the rocks thus relieved of the strain sprang back in opposite 
directions, causing a total lateral displacement of 125 yards. 
That this took place after the lodes were formed, and the original 
country rock was metamorphosed, can be seen by the faulting of 
the lodes, and by examining the orses of country rock enclosed 
in them. 
6.—ON THE APPLICATION OF PHOTOGRAPHY TO 
GEOLOGICAL WORK. 
By J. H. Harvey. 
7.—ON THE GEOLOGICAL STRUCTURE AND FUTURE 
PROSPECTS OF THE THAMES GOLDFIELD, NEW 
ZEALAND. 
By James Park, F.G.S., Director, Thames School of Mines. 
ALTHOUGH over twenty-two years have elapsed since gold was 
first discovered at the Thames, the geology of this goldfield has 
always been a subject of much discussion among New Zealand 
geologists, and even at the present time the most opposite and 
divergent views are held by different authorities, both as to the 
structure and true character of the rocks themselves. 
The mining operations of this field have so far been confined 
to an area little more than a square mile in extent, and as the 
more accessible and readily obtainable gold is being rapidly 
worked out, the question of deep-sinking and going further afield 
