Prof Sumner completed an MSc in Geography and HDE at the University of Natal in 1995. After two years on the staff at the University of Fort Hare he accepted a lectureship at the University of Pretoria in 1997. He completed a PhD on palaeo-environments of the Drakensberg in 2003, and was promoted to Associate Professor in 2007. He was a recipient of the UP’s Exceptional Young Researcher Award in 2005 and received his first NRF-rating in 2006. Recent research outputs have focused on practical aspects of rock weathering with particular application to the deterioration of San rock art.