Inverted Relief
Some areas of Mars show inverted relief, where features that were once depressions, like streams, are now above the surface. It is believed that materials like large rocks were deposited in low-lying areas. Later, erosion (perhaps wind which can't move large rocks) removed much of the surface layers, but left behind the more resistant deposits. Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water. On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces. Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River, Utah. Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.
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CTX image of craters with black box showing location of next image.
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Image from previous photo of a curved ridge that may be an old stream that has become inverted. Image taken with HiRISE under the HiWish program.
Read more about this topic: Terra Sirenum
Famous quotes containing the words inverted and/or relief:
“Ulysses ... is a dogged attempt to cover the universe with mud, an inverted Victorianism, an attempt to make crossness and dirt succeed where sweetness and light failed, a simplification of the human character in the interests of Hell.”
—E.M. (Edward Morgan)
“If the king is in the palace, nobody looks at the walls. It is when he is gone, and the house is filled with grooms and gazers, that we turn from the people, to find relief in the majestic men that are suggested by the pictures and the architecture.”
—Ralph Waldo Emerson (1803–1882)