76 ME. C. E. IILLEr OX THE GEAyiTE-GyEISSES '_Vol. Ixxvii, 



known deposits of Lo^vtr Palaeozoic age that have been recognized 

 within the area. The data from which the Pre- Cambrian age is 

 deduced are, therefore, of a comparative kind. 



The older rock series of Yorke Peninsula to which these Eyrian 

 rocks bear a close lithological and petrographical resemblance 

 are of definite Pre- Cambrian age, as proved by the presence of 

 Cambrian sediments on an eroded j^l^tfoi'm of the series, in the 

 Moonta and Wallaroo region. Apart from, this local correlation, 

 the complex bears a noteworthy similarity to the Pre- Cambrian 

 tracts of the Xorthern Hemisphere, and to none more than the 

 Lam'entian of Canada. 



Suj)erposed with a marked angular unconformity on the meta- 

 morphosed members of this older complex, and resting horizontally 

 on the deeply-eroded igneous types, are Tapper Tertiary sands and 

 ti-avertine. These deposits foriu a mantle to a considerable portion 

 of the region, and hinder the study of the older series over large 

 areas of country. Inland, in the hilly regions of the hundi*eds 

 of AYarrow and Hutchison, and to a less extent in the hundreds 

 of Louth and Lincoln, the older rocks are stripped of this mantle, 

 permitting a study of the complex. The best exposures, however, 

 are displayed along the coastline, where detailed studies can be 

 m.ade on the wave-swejDt platforms which fringe the coast. Here 

 the older rocks are usually within 100 feet of sea-level, and are 

 covered unconformably by consolidated sands of seolian origin. 



Precipitous cliffs are often developed, and occm- especially in the 

 hundreds of Flinders and Sleaford, where the coastal clilfs attain a 

 height of from 300 to -iOO feet. The older rocks contribute but 

 a small part to this elevation. 



Previous Literature. 



The literature bearing on the geological structure of Southern 

 Ep'e Peninsula is principally to be found in the publications of 

 the Geolosrieal Survev of South Australia. 



As the Survey investigations have been primarily made in order 

 to determine the possibility of the discovery of petroleum in this 

 area, but little detailed work has been done on the older complex, 

 and, so far as petrological investigation is concerned, the field up 

 to the time of the present enquiry can be regarded as untouched. 

 A summary of the available geological literature of the area is 

 appended to this paper. 



II. The Division's of the Pee-Cambeiax oe 



SOETHEEX EtEE PeN'IN'SULA. 



The division of the comj)lex into well-characterized groups or 

 series of rocks is largely hampered by the fact that sections of 

 these rocks, continuous over large areas, are seldom to be obtainecL 

 There are, however, despite this dominant mantle of calcareous 



