26 



■flat some four or five miles long by about a mile to two miles 

 wide, through which a rather large creek flows, and which in 

 former times was famous for its great fertility of soil. 



Tlie hills, dividing the two flats or wide valleys as well as those 

 on east and south, consist of micaceous and hornblendic schists, 

 ^and show here and there remarkably steep inclines. Those on 

 the west are much younger, and exhibit ferruginous shales and 

 conglomerates. Spurs extend far into the flat here and there. 

 The soil of the latter is on the surface, near the centre a black 

 tenacious clayey mould, but much more sandy nearer the margin. 

 Below this i s a dense extremely sticky grey or white clay, with 

 numerous fantastically-formed calcareous concretions. This 

 changes into sandy ferruginous loam, with lime nodules, which 

 has not been pierced by wells at a depth of 70 to 80 feet ; but 

 near the southern extremity, at 40 feet and less, pure sand and 

 coarse gravel was reached, bearing fresh water. These various 

 flats present semblances of the bottoms of a chain of lakes drained 

 by the bursting or w^earing away of comparatively narrow barriers 

 of hard rocks, and the flat at Lyndoch shows these features of 

 such lacustrine origin much more conclusively than the larger and 

 less hill-bound ones. 



The surface soil in the flat at Nuriootpa township along the 

 •course of the river is a rich black mould many feet in thickness ; 

 farther to the north a more or less adhesive clay prevails, as like- 

 wise towards the east from Nuriootpa. The township itself 

 stands upon a fertile sand, gradually merging into the sandhills 

 west and north-westward. South and south-east more or less 

 loose, either fertile or almost barren sand prevails to within a 

 mile of Tanunda. Below the sand and mould, which are of 

 slight thickness at places or missing altogether, follows first a 

 yellowish, sandy, and gravelly clay, in many places sufliciently 

 pure and plastic for bricks, and from 20 to 40 feet or more thick. 

 Underlying this and occasionally rising to the surface is a white 

 -and blue very adhesive clay, here and there stained deep rusty, 

 and which is remarkable on account of including layers of impure 

 salt, which were first observed in a bank of the river towards 

 Tanunda associated with thin hard layers of a ferruginous cement, 

 subsequently traced at various other places. No doubt this is 

 the cause why so many saline springs exist along the river. Even 

 the wells become brackish and finally undrinkable in those areas 

 which have this formation. As no fossils have been found the 

 age is doubtful, but I think may be assumed to be either the 

 latest Tertiary or early Pleistocene. The thickness seen varied 

 from about two feet to over five, but as this was near the edge of 

 the basin it must be much thicker in the middle. 



Under the blue clay follows a white, yellow, or red sandstone, 



