573 



appear, and can be traced on the descent towards the creek, 

 having a dip W. at 45°. At the most southerly bend in the 

 road the slates are reversed, dipping north-easterly, and 

 are very broken and rotten, with a confused dip. At about 

 half -distance frpm the crest of the road down to the creek 

 tho main quartzite shows a scarp face and is cut by the road. 

 At the western end of the scarp there is a strike-fault, which 

 hades westerly at 70°, with the quartzite on the one side 

 and purple-slates and thinnish quartzites (having a dip con- 

 formable to that of the fault-plane) on the other. Then the 

 talus once more hides the beds, but at the spur of the hill, 

 near the bottom of the road, there are again outcrops of 

 rotten slates, which dip north-westerly at 30°. At the base 

 of the hill, near the old smelting works, almost at creek level, 

 the slates dip W. 20° N. at 63°. After crossing Spring- 

 Creek the fault intersects the limestones on the opposite 

 banks, the beds being bent to a sharp angle and made to 

 take the strike of the fault-plane. 



The Spring Creek Copper Mine is situated near the 

 north-western angle of the mount. The ground in which the 

 mine is worked forms a rough, irregular, ferruginous outcrop, 

 making a scar on the face of the hill in bold crags, fifty 

 yards wide. Judging from stone at surface, the ore consists 

 mainly of red oxide and green and blue carbonates, set in a 

 broken fault-rock, which seems to be a mixture of Tapley 

 Hill slates and purple-slates. It is, probable that the mineral 

 deposits occur in the broken country at the intersection of 

 the main north and south fractures with the main east and 

 west fractures (in a multiplex system), which would account 

 for the two dissimilar shale beds being mixed together in the 

 lode-stuff. 



While the east and west fracture at the north end of the 

 mount is the main tectonic feature on that side, the gravi- 

 tational adjustments that followed on the collapse of the area 

 gave rise to several north and south fractures in the direction 

 of the general strike. This is made evident by the repetitions 

 of the limestone outcrops, as already described. It is prob- 

 able that this area is extensively faulted in this way, but it 

 is only when a well-defined bed comes into contact with the 

 fault-plane that the effects can be observed. The map shows 

 three such lines of fracture : — 



(a) On the western side of Spring Creek, where the 



limestone (faulted to the east) is cut off by the 

 purple -slates series. 



(b) About a mile to the eastward of the above, in the 



small creek the head of which is on the mine road 



