85 



from dolomitic to siliceous and relatively pure limestones.* No 

 marbles such as are found at Norman ville and Sellick's Hill are 

 known to occur in this series, and from a number of transparent 

 sections of the limestones of Brighton and Hallett's Cove, made 

 by Prof. David, it has been shown that the minute structure of 

 the stone is largely oolitic. The blue limestones of the last named 

 localities bear a close resemblance to the " blue metal" beds of 

 the Sellick's Hill section, but with the exception of casts of 

 Radiolariaf no fossils have been detected in the Brighton lime- 

 stones. It is a matter of great interest as to whether the Brighton 

 and Noarlunga limestones are comprehended in the same geological 

 formation as those of Sellick's Hill or not. The former follow a 

 general line of strike almost due North and South, whilst the 

 strike of the latter is from N.E. and S.W. to N.N.E. and S.S.W. 

 This slight discordance of strike in the respective beds is not in- 

 consistent with conform ability, but, taking the prevaling south- 

 easterly dip into account we must place the Brighton beds on a 

 somewhat lower geological horizon than the Sellick's Hill beds. 



Selwyn notes in his geological map an extensive anticline 

 running nearly parallel to the coast along the Aldinga Plains. 

 This anticline can be traced from Brighton to Normanville, and 

 is marked by a westerly dip on the coast with a general south- 

 easterly dip a few miles inland. This anticlinal area is 

 characterised by remarkable local contortions and overthrusts. 

 It is important to note that these crust movements have included 

 the Cambrians and the foot-hills of Mount Lofty in the same 

 great system of foldings. 



The discovery now recorded imparts new interest to the geology 

 of the Hills as a whole, and incites to fresh zeal in searching for 

 such evidences as will eventually unravel the connected story of 

 the origin and development of the great mountain system which 

 forms the geological axis of the colony. 



POSTCRIPT. 



Since reading the above paper I have revisited the neighbour- 

 hood of Willunga and followed the outcrop of the Cambrian lime- 

 stones for several miles beyond the point where left on my previous 

 visit. 



Three miles south-west of Willunga, on Section 545, owned by 

 Mr. Culley, sen., the calcareous beds, without making a bold 

 feature, crop out strongly along the foothills. They include the 

 siliceous limestones, flaggy limestones, and overlying quartzites 



* These limestones have, in part, been described by Prof. T. W. E. 

 David and W. Howchin, in a joint paper. Proc. Linn. Soc. N.S.W., 

 p. 571, 1896. 



t Op. cit. ante. 



H 



