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Murphy’s Haystacks: South Australia’s version of Stonehenge, estimated to be over 1,500 million years old

David Goran

Located at Mortana, between Streaky Bay and Port Kenny on the Eyre Peninsula, South Australia, Murphy’s Haystacks are a group of ancient, wind-worn pink granite boulders that were formed 1,500 million years ago.

They are just off the Flinders Hwy between Port Kenny and Streaky Bay on the Eyre Peninsula. Photo Credit

They are just off the Flinders Hwy between Port Kenny and Streaky Bay on the Eyre Peninsula. Photo Credit

 

They obtained their name because a traveller in a coach saw the formation in the distance. Photo Credit

They obtained their name because a traveller in a coach saw the formation in the distance. Photo Credit

It is believed that these granite rocks gained their name sometime between 1902 and 1914, when an agricultural adviser was passing by and saw what he believed to be haystacks. He asked the Owner of the property how they could produce so much hay, and after learning the truth, titled the rocks as “Murphy’s”- the Farmer who’s land they resided on.

Left - Formations. The overhanging dome is approximately 8 metres high. Right - The reverse side of the Haystacks. Photo Credit1 Photo Credit2

Left – The Formations. Right – The reverse side of the Haystacks. Photo Credit1 Photo Credit2

 

Located on the top of the hill in the western part of the Eyre Peninsula (South Australia). Photo Credit

They are one of the most popular and photographed attractions on the Eyre Peninsula. Photo Credit

These haystacks, of course, have nothing to do with farming and are in fact very fine examples of weathered granite inselberg structures, which often take the forms of boulders and pillars.

Tallest is approximately 8 metres high. Photo Credit

Tallest is approximately 8 metres high. Photo Credit

 

Murphy’s Haystacks are what geologists call inselberg, which forms when a body of hard rock surrounded by a layer of soft rock becomes exposed to erosion. Photo Credit

Murphy’s Haystacks are what geologists call inselberg, which forms when a body of hard rock surrounded by a layer of soft rock becomes exposed to erosion. Photo Credit

The process that created Murphy’s Haystacks began some 1,500 million years ago when boiling magma filled crevices below the earth’s surface and then cooled, laying down a granite base. The present formations were formed 100,000 years ago. The granite hills of the district, including the haystacks, were buried by calcareous dune sand. About 34,000 years ago they were uncovered by severe erosion, which exposed them in their present state as pillars or boulders, giving them fantastic shapes. Amazingly these beautiful pink granites were formed at a depth of 7 to 10 kilometres below the earth’s surface.

The “haystacks” continue to be eroded till this date. Photo Credit

The “haystacks” continue to be eroded till this date. Photo Credit

 

The site is listed on the South Australian Heritage Register. Photo Credit

Lichens, growing on the surface, paint these rocks with bright red colour. Photo Credit

The haystacks are located on a private property now belonging to Dennis Cash, grandson of Denis Murphy, who purchased the farm in 1889.