Kennedy Range is a weathered sandstone plateau, 12 to 25 kilometres wide and about 80 kilometres long, rising about 100 metres from the surrounding plain. It is an isolated remnant of an ancient land surface with 'outstanding geology' that can help 'unravel Australia's recent geological evolution'. As revealed by marine fossils, the area was once a marine shelf and fringing shoreline. Sand and silt were deposited and compressed over millions of years to form beds of sandstone and siltstone. The range was probably created by uplift about 20 million years ago and then eroded away.
The top of the Kennedy Range plateau is mostly a sandy plain of large red sand dunes and wide swales with spinifex grasses and shrubs. The eastern escarpment has dramatic sandstone cliffs dissected by steep canyons which turn into waterfalls after rain. This escarpment and its steep footslopes support tall shrublands of mulga and other wattles. The western slopes, with tall wattle shrublands and stony footslopes, are lower and less steep.