About Murphy's Haystacks
Mountain Peaks, Interesting Places, Natural, Geological Formations
Murphy's Haystacks are inselberg rock formations located at Mortana, between Streaky Bay and Port Kenny on the Eyre Peninsula in South Australia.
They are of a 'tumulus' form of weathered granite outcrop. They are made of a pink, massive, coarsely equigranular rock consisting mostly of quartz and orthoclase. Their appearance may be due to a combination of erosion by underground rainwater and then by subsequent weathering after they were exposed. Most of the pillars emerge without a break from the underlying granite. Their structural base may be of orthogonal or vertically-aligned sheet jointing.