Excerpt from Transactions and Proceedings and Report of the Royal Society of South Australia, 1886, Vol. 8

In the absence of paleontological evidence all identification of rocks based solely on their lithological features is open to a greater or less amount of doubt, but a faithfully recorded sequence of conformable strata in any one locality becomes a clue deserving consideration when examining neighbouring districts the topographical features of which suggest a relation thereto.

It has been shown that the upheaval of the western side of the Wakefield basin has had the effect of folding and faulting the beds of the upper group, producing. The swells which by denudation of the softer portions now form the numerous parallel ranges extending northward. In the troughs of synclinal folds, or along the line of faults, the numerous creeks have worn deep channels, and owing to this circumstance, i.e., the water following an indicated or ready-formed system of drainage, there are very few gorges or natural sections through out the whole district.

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 011 mica schists, and both are pierced by a large dyke of porphyritic greenstone. The whole of the Pekina Range, extending as far north as Oladdie Station, seems identical in structure to the Wakefield basin two unconformab'le 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 River, in which, according to Selwyn, the whole country 'is composed of one 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 Remarkable systems, and nearly on the central meridian line of the Flinders Range, when considered as a whole.

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