80 



off in that direction and are replaced by the flat 

 and sandy shores of Lake Torrens, makes a very 

 sharp boundary line, both topographically and 

 geologically. 



At the entrance to the gorge the Archaeo- 

 cyathinae limestones are at a lower level and 

 considerably lov^^er angle of dip than the great 

 scarp quartzite on which they rest. This strati- 

 graphical discordance may possibly represent 

 an angular unconformity in the geological suc- 

 cession, separating two series of beds that are 

 of different ages. Its evidence in this direction 

 is rendered doubtful, however, in that the 

 displacement (if such exists) occurs on the 

 nearly vertical face of the escarpment which 

 forms the eastern wall of the great South Aus- 

 tralian rift valley. This line of major faulting 

 is accompanied by many secondary fractures and 

 block faulting, the respective "blocks" settling 

 down at various angles. It was a matter of 

 regret that the necessary time could not be 

 spared for making such detailed observations as 

 might have settled this interesting question. 



The tectonics of the ranges are fundament- 

 ally based on periclinic and cycloclinic fold- 

 ings, together with much lateral movement. The 

 long curves of the folds can be noted from the 

 train, going north, from Mernmerna Station 

 (fig. 3). At the latter position, the western 

 scarps of the Elder Range make a bold feature ; 

 and a little further north, the western wall of 

 the Wilpena Pound Range is equally impressive. 

 A rough sketch of these mountains in section is 

 given here. 



Blinman occupies the centre of a great 

 earth movement of elevation. The tangential 

 forces have acted from all sides, almost equally, 

 with the effect that the whole district, from 

 Parachilna Gorge to Wirrealpa Old Sta- 

 tion, in a diameter of 20 miles, has been 

 raised in the form of a vast dome. The upper 

 beds form the outer rims of the dome, and the 

 centre, much reduced by denudation, exposes 

 the lower members of the series. According to 

 official figures, Blinman has a height of 

 2,020 ft. above sea level. Parachilna railway 

 station, on the plain, is 465 ft. above the sea 



