part 2] 



OF SOUTHERlSr EYRE PENINSULA. 



79 



In the hundred of Hutchison, outcrops are found along the 

 Port-Lincohi road, and, associated with members of the Hutchison 

 Series, they crop out in the hilh^ region west of Tumby Bay. 



Their extensions north of the hundred of Hutchison have not 

 been traced. The islands which frinsre the eastern coast of the 

 peninsula are formed of gneisses of the Flinders Series, notably the 

 Cape-Catastrophe group, and the Neptunes. They are largely 

 covered by recent calcareous sands. (See map, fig. 1.) 



F,g. 1 MAP OF 

 SOUTHERN EYRE PENINSULA 



Shewing the principal exposures 

 of the Flinders series in black 



West Point 



[b) Constitution. 



A diversity of rock-type is comprised Avithin the group. The 

 members include hornblende- and biotite-granite-gneisses, often 

 with a typical augen-structure, hypersthene- and diopside-granites 

 of the charnockite type, pegmatites and apHtes, and porphyritic 

 types, the pegmatitic varieties being especially characterized by 

 hornblende. 



This acid complex carries intercalated bands of basic rocks, 

 amphibolites, hornblende-schists, pyroxene-granulites, etc. 



The gneissic structure which is the dominant characteristic of 

 the granites is a primary structure, and represents a foliation 

 imparted to the rocks during their consolidation. 



