Before and after photographs taken many years apart show historic changes to some of the more notable topographic features of Kansas. Recently, several prominent erosional remnants have been modified or destroyed, including the Indian petroglyphs (Ellsworth County), Natural Bridge (Barber County), and Castle Rock, Cobra Rock, and the Sphinx (all in Gove County). These unique and interesting topographic forms were carved by water and modified by wind erosion. Although erosion rates are slow by human standards, catastrophic events can change or modify features rather drastically by any time standard.