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The limestone in these respective outcrops shows the 
characteristic features of the bed. It is commonly, finely 
oolitic in structure, and in shades of pink, blue, white, or 
brown. In contact with the main faults it is much altered, 
passing into yellowish, dolomitic, and ferruginous rock, 
whilst in parts still preserving its oolitic structure. In 
places a distinct fault rock is developed, calcareo-siliceous 
and jaspery. The purple slates on the line of junction be- 
come yellow, laminated, calcareous, and kaolinised slates, 
much weathered. The fault planes are more or less marked 
by quartz veins, carbonate of iron, and nodular brown 
ironstone. 
There are no doubt other minor faultings in this fieid, not. 
clearly defined, but suggested by the stratigraphical features 
that prevail. 
Siliceous and Earthy Limestones and Calcareous Shales. 
These beds directly underlie the main limestone, and are of 
much greater thickness. They exhibit in the Onkaparinga 
district the same wavy and vermiculate structure which 
characterises the corresponding beds further north. Through- 
out the district they participate in the same general dis- 
placements as have occurred with the main limestone which 
immediately overlies them. 
From the Field River they can be clearly followed through 
the township of Reynella; but southward of that township, 
at Morphett Vale, and extending beyond Hackham Post- 
Office, they are for the most part obscured by a thick cover 
of tertiary beds. 
A little south of» Hackham, in Section 32, an old quarry 
face is seen on the east side of the road, near the top of the 
rise. The stone is a siliceous banded limestone, with char- 
acteristic structure, having an exposed vertical face of about 
15 feet, dipping east-south-east, at 15°. On the eastern side, 
the siliceous limestone is obscured by Miocene sands; but the 
former rapidly widens to the southward, and spreads out 
into a series of beds, measuring a quarter of a mile across 
the strike. 
At Hackham main limestone quarry the siliceous lime- 
stones are seen to occupy the rise of the hill above the 
limestone ; whilst on the low side of the hill they are also seen 
to underlie the limestone, which is their normal position. The 
respective dips of the main limestone and the impure cal- 
careous beds which outcrop on its eastern side are discord- 
ant: the limestone dipping east-south-east, at a low angle, 
and the impure calcareous series, south-west, at 35°. On the 
north - and - south district road, near the eastern limits of 
the outerop, the dip of the last-named beds is reversed to 
south-east, at 33°. This repetition of the impure calcareous 
