Composed mainly of chalk and clay excavated from the surrounding area, the mound stands high and covers about . The hill was constructed in several stages between 24002300 BC and displays immense technical skill and prolonged control over labour and resources. Archaeologists calculate that it took 18 million man-hours, equivalent to 500 men working for 15 years to deposit and shape of earth and fill. Euan Mackie asserts that no simple late Neolithic tribal structure as usually imagined could have sustained this and similar projects, and envisages an authoritarian theocratic power elite with broad-ranging control across southern Britain.