274 



Spencer. Tha<t this line approaches the present westerly limit 

 of the glacial Till is shown by the fact that the Pleistocene 

 sands rest directly on the metamorphic rocks at all the prin- 

 cipal headlands on this part of the coast, the clay in all cases 

 being absent. 



Further Glacial Evidences. 



In a small lagoon a quarter of a mile east of Moorowie Head. 

 Station, two large erratics of granite occur, measuring 7 ft. x 6 

 ft., and 3 ft. x 1 ft. respectively, exposed abo\e the land surface. 

 Several smaller erratics (one of which a microscopical section 

 has shown to be diabase) were seen in the adjoining fields. 



On the western shore of Davey's Lake, Section 478, Melville, 

 due south of Pink Lake, over 100 erradcs were counted, many 

 of them being of considerable size. The two largest consisted 

 of quartzite and granite respectively, and measured 3 ft. x 2 ft. 

 6 in. and 2 ft. x 18 in. exposed above the surface ground, the 

 granite being chiefly characterised by large crystals of ortho- 

 clase. The smaller stones consisted mainly of quartzite and 

 granite. A small erratic also occurs beside the main road to 

 Corney Point at the junction of Sections 158 and 159, Carribie. 

 In all cases the different rocks of which the erratics are com- 

 posed may be seen in situ in various localities along the south 

 and west coasts. 



Archean. 



Rocks of this age are very widely distributed over southern 

 Yorke Peninsula, underlying the glacial clay, and forming the 

 basal portion of nearly all the headlands on the west and south- 

 west. In general they are gneissic in character, and show no 

 traces of a sedimentary origin, unless it be in some very ob- 

 scure ( V) bedding in some of the rocks at Point Souttar. In 

 nearly all cases they are highly contorted, aaid show large 

 developments of biotite along the lines of foliation, indicating 

 a. very advanced state of metamorphism, which, as a rule, 

 becomes more pronounced as the southern portions of the 

 Peninsula are approached. 



Metamorphic rocks first appear at Brutus Castle, on the 

 north-west coast, as low reefs of aplite and fine-grained horn- 

 blendic gneiss, the latter passing into hornblendic schist 

 where the crushing has been extreme. In this outcrop, which 

 extends along the coast towards Corney Point for about four 

 miles, a very remarkable rock occurs, consisting of a granulitic 

 base of quartz and pink felspar with ragged sections of a very 

 strongly pleochroic amphibole, the predominant color of which 



