Murphy’s Haystacks are a picturesque group of ancient, wind-worn rock of pink granite situated between Streaky Bay and Port Kenny on the Eyre Peninsula in South Australia. The Murphy’s Haystacks placed in the middle of a wheat field and surrounded by mallei scrub, they’re one of the most prominent and photographed magnetisms on the Eyre Peninsula. Therefore, Murphy’s Haystacks are what geologists named it “inselberg”, which are well isolated rocky hills or ridges that rise briskly from a gently sloping or particularly level surrounding plain. An inselberg forms when a body of hard rock surrounded by a layer of soft rock becomes uncovered to erosion. The less resistant outer layer is eroded away to form a plain, leaving the extra resistant rock behind as an isolated mountain.
The procedure that formed Murphy's Haystacks initiated somewhere 1,500 million years ago when hot magma filled crevices below the earth’s surface and then ventilated, laying down a granite base. The current formations you see at Murphy’s haystacks were shaped 100,000 years ago and were buried beneath earth until around 34,000 years ago when they were exposed by terrible erosion, which uncovered them in their current state as pillars or boulders. The “haystacks” carry on to be eroded till this date, giving them bizarre shapes. The haystacks are situated on a private property belonging to Dennis Cash, the grandson of “Denis Murphy”, who actually buys this farm in 1889. The inselbergs were famous with friends and family, and could be seen from the void by the passengers of the local mail run stagecoach. However, many legends say that once a protuberant agricultural proficient was passing by the farm when he saw the landmark from the road. Though not realizing that they were rocks, the man remarked “the farmer must have plowed his land to create such an inspiring profusion of hay”. The mail coach driver, being a local man be familiar with they were on the Murphys' property. Although from then on the amused his passengers by referring to the isolated inselbergs as ‘Murphys Haystacks’.Source: Amusing Planet