243 



the gorge, theie is a conspicuous fault dyke in tlie centre of 

 the quarry, 2 feet thick, having well-defined walls, and iiades 

 10° east. The dyke consists of brecciated quartzite and quartz, 

 the whole mass thickly penetrated by dendrites. 



The beds being tliin and much jointed, the stone is only 

 used for road metal, and is easily won. The dip of the beds 

 swings round between south-west and south-east, at from 18' 

 to 25 . Tlie steepness of the face, the extensive jointing of 

 the beds, and the dip being towards the gorge, have had the 

 effect, in wet weather, of bringing down great slides of stone, 

 damming the creek and blocking the road. 



The Fourth Creek ( Morialta). — The thick quartzite, 

 which forms tlie high range on the north side of the Fourth 

 Creek, is undoubtedly the same as that of the Black Hill, but 

 it is a distinct fragment. The Black Hill is determined by 

 faults, both on its west and south sides. The west fault is a 

 continuation of the great displacement which runs along the 

 western slopes of the hills, and the fault on the south side 

 follows the direction of the Fifth Creek. The latter has 

 broken the continuity of the thick quartzite, and thrown it 

 further to the east between the Fifth and Fourth Creeks. 



Stnnyfell presents another isolated fragment of the thick 

 quartzite, almost equallino- the Black Hill in magnitude. The 

 beds for the most part have a comparatively low angle of dip 

 directed to the south-west, but the dip increases towards the 

 western side, where the beds roll, and are intensely disturbed 

 as they near the important fault which skirts the foot-hills. 

 The fault-plane can be well seen in Dunstan's extensive 

 quarries. The strike of the fault here is 35° east of north, 

 and can be traced along the outcrop, both north and south. 

 It is well seen in the Fourth Creek and between the Fourth 

 and Fifth Creeks. The zone of fault-fracture in the quartz- 

 ite at Stonyfell is about 50 yards wide, in which the rock is 

 much brecciated, and penetrated by quartz veins. The quartz- 

 ites are thrown against the slates, and the slates dip towards 

 the fault-plane. At the fault their dip is 55° east, and in 

 a short distance away, in a small quarry on the old road, the 

 dip is 35^ in the same direction. The quartzite comprises the 

 high ground to the south of Stonyfell, which is intersected by 

 Slape's Gully, and is limited, in the main, on that side bv th^ 

 Greenhill road. At Stonyfell, as in all cases with the thick 

 quartzite, the stone is exclusively used for road metal. 



Mount Lofty — Mount Lofty owes its prominence to the 

 thick quartzite, which forms its summit, and is there nearlv 

 horizontal in position. The ridge which connects the Mount 

 with Crafers forms a continuous outcrop of the same beds, and 



