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Point platform, where the PHocene bed rests directly on the glacial beds, but it 

 puts on suddenly at the northern side of the Cove, where for some distance it 

 makes a thick though variable bed underlying the Pliocene. It is absent where 

 the Pliocene beds are seen resting on the Cambrian, at Marino, and is also absent 

 from the cliffs to the northward of Rocky Point, where the Pliocene beds make 

 a sharp plane of contact with the purple slates, yet, within a short distance, to 

 the southward, it develops a considerable thickness inferior to the Pliocene. The 

 possible relationship of this bed to a similar bed that occurs at Hallett's Cove, and 

 also on Kangaroo Island, has been mentioned previously. The question is — there is 

 a white sand rock underlying the fossiliferous Pliocene in some places while absent 

 in others — Can all these white sand beds be referred to a common origin, or have 

 they different origins? If the bed had been limited to the Hallett's Cove section 

 it would no doubt have been referred without hesitation to the Glacial Series. 

 On the other hand, if only the bed, occupying the same stratigraphical position 

 near the outlet of the Morphett Vale Creek, had to be accounted for, the ex- 

 planation that would come readiest to mind would be that it represents a 

 residual portion of the Freshwater Series, that underlies the fossiliferous Miocene, 

 which occurs in outcrop at no great distance to the southward. In such a case it 

 must be assumed that the marine beds of the latter, and more or less of the 

 underlying freshwater beds, had been removed by denudation before the fossili- 

 ferous Pliocene was laid down, and when the latter rests on Pre-Miocene rocks, 

 it would follow that the whole of the freshwater beds, inferior to the Miocene, 

 had been removed before the deposition of the Pliocene. 



Tectonic Deformations. 



The deformations of the Tertiary beds within the area under description 

 have relation to the tectonic movements that have contributed towards shaping 

 the present physiographical features of the country. The two main controlling 

 factors in this respect are : (a) The subsidence of the land in the Adelaide basin, 

 in successive segments, by which the Miocene beds have sunk below the surface 

 at various levels and, subsequently, been covered by newer deposits, (b) The 

 breaking up of the ancient peneplain into faulted earth-blocks that have produced 

 the south-westerly slopes of the Mount Lofty and Willunga Ranges. 



In sympathy with such regional dislocations the Tertiary beds within the 

 area have taken on a general south-westerly dip. The regularity of this dip-slope 

 is interrupted by a repetition of beds. At Witton Bluff the basal beds of the 

 Tertiary system are exposed on the northern side of the Bluff with a gradual 

 dip to the south-west which brings in the higher beds, ending with the Pliocene 

 at sea level on the northern side of Pedler's Creek. On the southern side of 

 Pedler's Creek an inlier of Cambrian beds once more brings the basal beds of the 

 Tertiary systems to the surface, followed by another gentle dip-slope to the south- 

 west which, from Blanche Point, brings in the higher members of the series 

 ending with the Pliocene, once more down to sea level, near Snapper Point. 

 This interesting feature of repetition of the Tertiary system no doubt owes its 

 existence to an east and west fault with a downthrow on the north and an 

 upthrow on the south. The remarkable occurrence of an isolated fragment of 

 the fossiliferous Miocene on the line of fault is a corroboration of its existence, 

 for this fragment lies directly between the topmost Tertiary bed on the northern 

 side of Pedler's Creek and the lowest (freshwater) Tertiary bed on the southern. 

 It therefore owes its existence to a trough fault. 



The coast adjacent to Sellick's Hill forms a part of the great fault-block 

 of the Vv^illunga Ranges. The Miocene beds in this region were, originally, laid 

 down horizontally on the broken edges of the Cambrian strata and were elevated 

 to a considerable height at the plateau formation period. A remnant of this 



