315 



some undoubted radiolaria in high relief, with a central 

 capsule. To my mind there is no doubt that these remains 

 are radiolarian." 



The siliceous and laminated limestones that underlie the 

 Brighton main limestone exhibit remarkable structures in 

 which calcareous and argillaceous material, in separate 

 fragments, are interlaminated. From the resemblance which 

 this rock makes, in cross section, to vermiform bodies it has 

 been called '"vermiculate" structure. <25) The origin of this 

 structure is under investigation. 



The Burra (Kooringa). 

 Pis. xvii. and xviii. 



The Burra, which is the railway station for Kooringa, is 

 situated on the main north line, 101 miles, by rail, from 

 Adelaide. The Brighton limestone series is extensively 

 developed in the neighbourhood, and although lacking in the 

 particular textural features now under description, it is 

 w^orthy of some notice here. 



Tliere can be no doubt as to the geological horizon as 

 the limestone is underlain by the banded slates, and within 

 two miles of Kooringa, on the eastern side, there is an 

 extensive outcrop of the Sturtian Tillite, which is the correct 

 order of succession. The beds have been greatly disturbed by 

 folding, faulting, and overthru sting, which have produced 

 a certain measure of metamorphism that has rendered them 

 dissimilar from the rocks of the same horizon both to the 

 south and north of them. No good natural sections occur in 

 the neighbourhood, so that observations are almost limited to 

 the few quarries that have been opened. The most important 

 of these is the Government ballast quarry, on the western 

 side of the railway, not far from the station. The great open 

 cut at the old mine is in very broken country, including a 

 thick band of fault-breccia, so that it is of little service for 

 stratigraphical determinations. The upper members of the 

 Brighton series, which are massive and carry the oolitic-like 

 bodies and brecciated structure, are apparently absent from 

 the Burra outcrops, having been denuded, and the structural 

 features that are present agree, in a general way, with the 

 siliceous limestones that underlie the main limestone in the 

 true order of succession. The limestones are, characteristically, 

 finely laminated in parallel lines of different shades of 



(25) Howchin, ''Geology of Mount Lofty Ranges," part 1, 

 Trans. Roy. Soc. S. Austr., vol. xxviii., 1904, p. 263, et seq. 

 Howchin, "Geology of South Australia," 1918, p. 358. 



