Monday, September 22, 2008

Ius Chasma

- Photo Credit: NASA

The Red Planet is home to Valles Marineris, the solar system's largest canyon. Within this canyon lies Ius Chasma. This image, which spans the floor of its southern trench,m was taken by the Mars Reconnaissance Orbiter. The canyon is well-known for its fine stratigraphic layers modified by wind and water.

The outcrops contain interchanging layers of dark and bright rocks. The layered deposits consist of dark basalt lava flows and bright sedimentary layers. The sediments are likely to be from atmospheric dust, sand or alluvium from an ancient water source. The layers are visible on the gentle slopes above the canyon floor, in pitted areas, and in small mesa buttes. The floor of the canyon is littered with megaripples that are aligned in a north-south direction.

Ius Chasma is believed to have been shaped by a process called sapping when water seeped from the layers of the cliffs and evaporated before it reached the canyon floor. Ius Chasma also has several structural features such as east trending normal faults and grabens that deformed the canyons. Recent geomorphological events include avalanches and minor sapping from gullies that continued to erode the canyon walls.

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