Murphy's Haystacks are

inselberg An inselberg or monadnock () is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa a similar formation of granite is known as a koppie, a ...

rock formations located at Mortana, between

Streaky Bay Streaky the Supercat is a fictional superhero cat that appears in comic books published by DC Comics. He first appeared in ''Action Comics'' #261 (February 1960) and was created by Jerry Siegel and Jim Mooney. He is Supergirl (Kara Zor-El), Su ...

and Port Kenny on the

Eyre Peninsula The Eyre Peninsula is a triangular peninsula in South Australia. It is bounded by the Spencer Gulf on the east, the Great Australian Bight on the west, and the Gawler Ranges to the north. Originally called Eyre’s Peninsula, it was named aft ...

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

. They are of a 'tumulus' form of weathered

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

outcrop. They are made of a pink, massive, coarsely equigranular rock consisting mostly of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

and

orthoclase Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles t ...

. 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 In mathematics, orthogonality is the generalization of the geometric notion of ''perpendicularity''. By extension, orthogonality is also used to refer to the separation of specific features of a system. The term also has specialized meanings in ...

or vertically-aligned sheet jointing. They obtained their name because a traveller in a coach saw the formation in the distance. He asked how a farmer could produce so much

hay Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticat ...

. As the farm was on a property owned by a man called Murphy, the rocks became known as Murphy's Haystacks. The site is listed on the

South Australian Heritage Register The South Australian Heritage Register, also known as the SA Heritage Register, is a statutory register of historic places in South Australia. It extends legal protection regarding demolition and development under the ''Heritage Places Act 1993'' ...

References

External links

District Council of Streaky Bay webpageMurphy's Haystacks - Ancient Granite RockMurphy's Haystacks YouTube
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