55 



land-slips, exposing smooth faces of rock from which the 

 material has slid. The evidences submitted seem to point to- 

 only one conclusion, that in the locality under review there 

 was a common movement of the earth's crust in which both 

 the Cambrian and Cainozoic rocks were equally involved. 



We must now attempt to decipher the nature of these 

 earth movements. 



It can be safely assumed that a great fault-fissure follows 

 the base of the Willunga scarp, running in a north-easterly 

 direction, and is marked by the valley in which the townships 

 of Bellevue, McLaren Vale, and Kangarilla are situated. 

 Although the exact line of fault is obscured by thick deposits 

 of alluvium, its presence is clearly indicated by the dis- 

 cordance of the strike in contiguous areas and other features. 

 In the Mount Lofty Ranges the general strike is approxi- 

 mately north and south, while the strike in the Willunga 

 Ranges is east 40° north. The existence of such a fault has 

 long been inferred and has now received confirmation by the 

 collateral evidences obtained on the seacoast near Sellick's 

 Hill. The Sellick's Hill coast section does not demonstrate the 

 existence of a north-easterly fault in a direct way, but gives 

 it a high probability, indirectly, in showing that there is a 

 corresponding earth movement facing the sea with which it 

 can be correlated. It is an example of block-faulting on a 

 large scale. A segment of the earth's crust has been frac- 

 tured and tilted. The throw of the rocks has exposed two 

 sides of the fractured block in prominent scarps, which, as 

 already explained, intersect to form an obtuse angle — the 

 Willunga Ranges, forming one limb of the block, and the 

 sea cliffs and Myponga Ranges, the other. The Willunga 

 scarp gives an average height above sea-level of 1,200 ft. 



We can take a step further in our investigations, and 

 conclude that the earth movement, so far as the Willunga 

 segment is concerned, was in the direction of an uplift amount- 

 ing at least to 1,200 ft., bordered on its northern and western 

 sides by downthrows. Looking from Sellick's Hill north- 

 wards a great land-slope is seen, rising northerly, until it 

 finds its culmination in the Mount Lofty ridge. On this 

 slope, the highest bed, geologically, occupies the lowest posi- 

 tion at the base of the Willunga Ranges; while the 

 lowest bed, geologically, occupies approximately the highest 

 position along the ridge of Mount Lofty. Here we have the 

 rough outline of another great faulted block showing a down- 

 throw to the Willunga scarp. 



Another item of evidence in proof of the uplift of the 

 Willunga segment is gathered from the distribution of the 

 Eocene beds within the area. The most distant, as well as the 



