74 



Westward of the township, further developments of a 

 similar gneiss, with occasional patches of true granite out- 

 crop at intervals along the old Lake Wangary Road to its 

 summit; at this point an interesting series of rocks, with 

 features more strongly suggestive of a meta-sedimentary 

 origin than any previously noted, is met with. Fine grained 

 felspar-actinolite, mica-felspar-quartz, and epidote-quartz 

 schists alternate in narrow bands with each other. Amongst 

 these is a beautiful actinolite-felspar-quartz schist, in which 

 the actinolite has taken up a radial arrangement identical in 

 appearance with specimens collected at Rocky Gully, near 

 Murray Bridge. Further gneissic rocks, with structures 

 strongly suggestive of a sedimentary origin, outcrop on the 

 west side of Winter Hill. An isolated bed of fine-grained 

 quartz-felspar schist was noted outcropping on the far side of 

 Pinch Swamp. 



At Tumby Bay the most attractive feature of the old 

 rocks is a wonderful development of marble in all stages of 

 silication. This belt of rock, though highly metamorphosed, 

 is readily distinguished, and can be followed from near Lip- 

 son Cove, in a south-west direction, past the Port Lincoln 

 Copper Mine, and no doubt extends far in the direction of 

 the Marble Range. Magnesian minerals are largely develop- 

 ed in this belt, serpentine, asbestic, talc, and magnesite being 

 fairly abundant. In places, silication has advanced so far 

 as to produce a nearly pure wollastonite rock. 



Bordering on this metamorphic-marble belt are thick 

 strata of highly crushed rock, in which are abundant pseudo 

 pebbles of granulated quartz and felspar; these are embedded 

 in a schist base of fine particles of the same materials, with 

 abundant highly pleochroic (light yellow to deep red) mica 

 and garnets. Some beds in this zone are so exclusively com- 

 posed of garnets as to assume the character of garnet rock ; 

 specially good examples of such are met with a few yards 

 west of both the Port Lincoln Copper Lode and the Burra- 

 wing Lode. 



At the Port Lincoln Mine, which is on the south-east 

 side of the marble belt, the strata dips steeply to the north- 

 west, whereas an opposite dip was recorded further to the 

 north-west. This fact, taken in conjunction with a sharp 

 syncline observed in certain overlying quartz-felspar schists, 

 possibly indicates a synclinal trough. On either side of this 

 belt, trending in a parallel direction, are rocks of a more 

 igneous character. 



Southward, towards Yalluna, is a broad series of gneissic 

 rocks, very beautifully lined, darker areas composed of 

 granular orthoclase, quartz, magnetite and much sea-green 



