Geology
Para Wirra Recreational Park lies entirely within an inlier of crystalline basement rock which extends southwards to Torrens Gorge. It is part of a more extensively exposed Precambrian rock mass, the oldest in the Mount Lofty Ranges. In the extreme west of the park there are undifferentiated metamorphic, mostly very micaceous rocks (schists), and gneisses. A zone of distinctive layered or banded quartz-feldspar rich rocks (gneisses) extends though the central portion of the park. In the extreme east there is another conspicuous rock type (augen gneiss) which is distinguished by the presence of “eye” structures (usually of feldspar) up to 2.5 cm in length, indicative of greater shearing.
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