Speculation as to their use range from 'markers where particular astronomical events can be observed;' to myths including 'they are made by the devil throwing a stone finger or javelin or thunderbolt.' The photograph was taken on a bright summer day, but it still came out dark, giving it an air of mystery!
A similar theory is that, 'colossal stones, some as large as mountains, could be physical evidence for interplanetary lightening bolts....' (source http://www.thunderbolts.info/tpod/2007/arch07/071029monoliths2.htm )
A further site suggests that these structures are aligned to the movements of the sun. moon and even the stars. Which poses the question; 'how could such knowledge have been known long before the compass was invented?'
If monoliths are aligned to planets who could they possibly benefit? Another area featuring monoliths is West Yorkshire, the Long Stoop near Mankinholes, Todmorden. It was in this very area in November 1980 that a police officer Allan Godfrey (whilst on duty) encountered a UFO!