Inverted Features on Mars

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Imagine a river or lake on Earth. What would it look like if you took all the water out? Something like this:

Dry Riverbed in the Himalayas

On Earth, when a riverbed dries out it leaves a depression, or indentation in the Earth.


So then why on Mars are riverbeds and lakes inverted, or raised features, like in the below image of Gorgonum Basin?




Gorgonum Basin. Credit: HiRISE (Click through for HiRISE captioned image)

or Iani Chaos?



Iani Chaos. Credit: THEMIS (Click through to post on this image)

It all comes down to erosion. The weight of the water condenses and compacts the sediment beneath it, making it much harder and more resistant to wear from erosion. Thus, over the course of millions (and sometimes billions) of years, the ground surrounding the river bed gets eroded much more rapidly than the riverbed itself. This results in the inverted features that you see on Mars today.

Mars Photo of the Day - Sept 5 2011

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Today's Mars Photo was taken by the European Science Agency (ESA)'s Mars Express. This photo of Mars is evidence that a massive lake once existed within Eberswalde Crater, which measures 65 km in diameter.

The delta is thought to have formed 3.7 billion years ago during the Hesperian Epoch, when an asteroid struck the Martian surface. Prior to this discovery it was thought that Mars was a barren, frozen planet, during the Hesperian Epoch, but the existence of this lake proves that there was liquid water present on the planet.

To see the enlarged photo click on the image. See a related, more in-depth article at The Daily Galaxy

See All Mars Photo of the Day Posts!