part 2] OF SOUTHEEIN' ETIIE PENINSULA. 77 



sands and lateritic ironstone, certain features which can be singled 

 oat as characterizing tj^pes of rocks, and the following divisions 

 or series are recognized : — (a) The Hutchison Series, (5) The 

 Flinders Series, (c) The Warrow Series, and (d) The Dutton 

 Series. 



The division calling especially for treatment in this paper is the 

 Flinders Series ; but a brief statement is necessary concerning the 

 nature and constitution of the remaining series. 



(a) The Hutchison Series. 



Some members of this series have already been described : 

 namely, the dolomites and calc-magnesian silicate-rocks,^ the para- 

 gneisses, ^ and the graphite-rocks.'^ This formation is predomin- 

 antly of sedimentar}^ origin. 



The sequence of rocks, and further subdivision of this series, if 

 ever possible, must await a detailed examination of the hundred 

 of Hutchison, and its northward extension, where these rocks are 

 extensively developed. 



The Sleaford-Bay area gives some idea of the complexity of this 

 formation, which has been invaded and cut up by later igneous 

 intrusions. 



The strata strike in a north-and-south direction, swinging to a 

 north-easterlj^ direction in the northern exposures. This may be 

 appropriately called the 'graphite line,' as the occurrence of graphite 

 is, so far as is known, confined to the metamorphosed sediments 

 which are grouped within the Hutchison Series. 



(b) The Flinders Series. 



This is the most widespread member of the group. It consists 

 of a complex of igneous rocks : granites and gneisses with asso- 

 ciated basic rocks, amphibolites, hornblende-schists, and jD^TOxene- 

 granulites. 



Its relation to the Hutchison Series is alwaj^s of the intrusive 

 kind. A section has been given, in the papers to which reference 

 is made above, of the Hutchison Series invaded and metamorphosed 

 by sills of the Flinders gneisses. 



(c) The Warrow Series. 



This is a metamorphosed sequence of sediments, principally 

 developed in the hundreds of Warrow and Lake Wangary. The 

 rocks are quartzites, slates, and mica-schists. 



This group is distinct from the Hutchison Series, its chief 



1 Geol. Mag-. 1920, pp. 449-62, 492-500. 



2 Ihid. 1921, p. 251. 



3 'Economic Geology' 1921, pp. 184-98. 



h2 



