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 and

Port Kenny Port Kenny is a small town located on the Eyre Peninsula in South Australia. It serves as a central point for the surrounding agricultural district, as well as professional fishermen and tourists. It currently has a very small population. Hist ...

on the Eyre Peninsula in

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 und ...

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 ...

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 angl ...

. 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 Sheet or Sheets may refer to: * Bed sheet, a rectangular piece of cloth used as bedding * Sheet of paper, a flat, very thin piece of paper * Sheet metal, a flat thin piece of metal * Sheet (sailing), a line, cable or chain used to control the ...

. 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. 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
{{coord, 33, 00, 54.7, S, 134, 29, 19.67, E, source:nlwiki, display=title Landforms of South Australia Eyre Peninsula Rock formations of Australia South Australian Heritage Register