Antelope Canyon. Shaft of sunlight reaching through the eroded sandstone walls of Upper Antelope Canyon, a slot canyon in Arizona, USA, at noon. The smooth angular surfaces of rock have been eroded by seasonal flash floods after thunderstorms, as the water, which contains sand particles. follows cracks in the sandstone. Localised turbulence and eddy patterns in the flow of water cut natural arches, curves and holes into the rock.