"What lies beneath the quartzites of the lower group is not 

 visible in this district, but in the northern areas, at Tarcowie 

 Springs, in the Appila Creek, a similar series of beds — which 

 for the reasons just given I assume are identical with the 

 Wakefield group — rest directly on mica schists, and both are 

 pierced by a large dyke of porphyritic greenstone. The whole 

 of the Pekina Itange, extending as far north as Oladdie 

 Station, seems identical in structure to the "Wakefield basin — 

 two unconformable series of beds, the one principally argilla- 

 ceous, the other chiefly calcareous and siliceous. Between the 

 Pekina and Wakefield beds lies the basin of the Broughton 

 E/iver, in which, according to Selwyn, the \vhole country is 

 composed of oue single series of rocks in anticlinal and syn- 

 clinal undulations extending from Bundaleer to the foot of 

 Mount Bryan. This series I have traced into direct connection 

 with what I have termed the " upper group" in the foregoing 

 pages, and despite the absence of fossil evidence the inference 

 is a very strong one that the Pekina and Wakefield " lower 

 group" rocks are identical. We have thus an axis of upheaval 

 extending from the latitude of Port Augusta to the shores of 

 St. Vincent Gulf quite distinct from that of the Hummocks 

 and Mount Eemarkable systems, and nearly on the central 

 meridian line of the Flinders E-ange, when considered as a 

 whole. 



South of Kapunda the Adelaide chain has been so meta- 

 morphosed that lithological aspects on a large scale cannot be 

 grouped in such a manner that the rocks shall of themselves 

 bear the impress of identity, but the numerous references 

 given by Selwyn indicate that the sequence of each conforma- 

 ble series will yet suffice to connect them with the two groups 

 of the Wakefield basin. 



EXPLANATIOSr OE PLATE I. 



The sectional line runs from Port Wakefield slightly north 

 of east to the Murray Plats beyond Eudunda. From the 

 Dalkey Eauge to the Hermitage Hill, the beds vary much in 

 strike and dip and one bed is distinctly inverted. One mile east 

 of Ehynie the faulted beds dip north-westerly, and the line of 

 strike is only 25° from that of the section. The table-lands 

 range is crossed at about 15° less than a right angle. All the 

 other portions of the section are in the direction of the true 

 dip or at right angles to the line of strike. — J. J. E. 



