Inverted relief

Inverted relief, 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. Inverted relief has been observed on the surfaces of other planets as well as on Earth. For example, well-documented examples of inverted topography have been discovered on Mars.

Several processes can cause the floor of a depression to become more resistant to erosion than its surrounding slopes and uplands:

A classic example of inverted relief is Table Mountain, Tuolumne County, California. Multiple lava flows filled an ancient fluvial valley that cut westward through the central Sierra Nevada to the Central Valley about 10.5 million years ago. These Miocene lava flows filled this ancient river valley with a thick sequence of potassium-rich trachyandesite lavas that are significantly more resistant to erosion than the Mesozoic siltstone and other rock in which the valley was cut. Thus subsequent differential erosion left these volcanic rocks as a sinuous ridge, which now stands well above landscape underlain by more deeply eroded Mesozoic rocks.

Inverted relief in the form of sinuous and meandering ridges, which are indicative of ancient, inverted fluvial channels, is argued to be evidence of water channels on the Martian surface in the past. An example is Miyamoto Crater, which was proposed in 2010 as a potential location to be searched for evidence of life on Mars.

Other examples are shown in the photographs below.

CTX image of craters with black box showing location of next image.

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