Murphy's Haystacks are an example of a geological formation known as an iselberg. They are formed by the weathering of crystalline rock. Fractured sections wear faster than the unfractured sections. The pink rock, in Murphy's haystacks is hiltabe granite which formed about 1.5 billion years ago. The iselbergs are only 100,000 years old.
Amongst these iselbergs I vision aboriginal corroborees thousands of years before the arrival of Europeans. Turning only slightly, visions of pre-European corroborees are brutally destroyed by a shed, a paddock, a cylindrical concentrate toilet and in the distance, a wheat silo.
There are a number of iselbergs on the Eyre Peninsula. Another is Pildappa rock, also known as wave rock, near the town of Minnipa. This is because from some angles, it does look like a wave. Its shape has been sculptured by subterranean weathering proceeding faster than surface weathering. On the surface, because the water has evaporated, weathering occurs at a slower rate.
Over aeons the ground eroded away exposing a concave surface. Its surface is covered with small pool basins called gnammas and water worn grooves called rillens. Looking at the rillens and gnammas brings the realization that this would be much more spectacular scene after a heavy rain storm.