Inverted topography or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most often occurs when low areas of a landscape become filled with lava or sediment that hardens into material that is more resistant to erosion than the material that surrounds it. Differential erosion then removes the less resistant surrounding material, leaving behind the younger resistant material which may then appear as a ridge where previously there was a valley. Terms such as "inverted valley" or "inverted channel" are used to describe such features. Plateaus, mesas and buttes may also be formed as inverted features. Examples of inverted topography have been discovered on Mars.
Topographic inversion should not be confused with folding, a geological process in which rock strata shift position because of tectonic forces or kinetic impact. Inversion is something like molding and casting (see Sand casting), in which the feature remains stationary, but changes its elevation relative to the surrounding surface. In the image at right, channels on Mars became ridges through the processes of sedimentation and differential erosion.