The Interior of Mars

The current understanding of the interior of Mars suggests that it can be modeled with a thin crust, similar to Earth's, a mantle and a core. Using four parameters, the Martian core size and mass can be determined. However, only three out of the four are known and include the total mass, size of Mars, and the moment of inertia. 

Martian Atmosphere

This oblique image taken by the Viking orbiter spacecraft shows a thin band of the Martian atmosphere. This image looks northeast across the Argyre basin. The Argyre basin is about 600 kilometers across with a rugged rim of about 500 kilometers in width. 
White Rock

This image shows a lesser known, but unusual feature on Mars. It is commonly called "White Rock". The white feature is eroded crater fill, but exactly how it was formed has not been satisfactorily explained. White Rock was not formed by polar processes because it lies near to the equator at latitude -8 degrees and longitude 355 degrees. It has been modified through Aeolian erosion showing transverse and longitudinal erosional features. 

Polar Laminated Terrain

Viking 2 spacecraft took this picture of the Martian north polar cap. The visible layering occurred as a result of wind born dust settling upon the polar cap. As the caps experience climatic variations, they expand and contract. The layers of dust sediment tend to grow thicker near the poles where ice deposits remain for longer periods of time. The thickness of the deposits indicates they were formed during cyclical climatic variation rather than annual changes. 

Valley Network
These features show a resemblance to drainage systems on Earth, where water acts at slow rates over long periods of time. As on Earth, the channels shown here merge together to form larger channels.

However, these valley networks are less developed than typical terrestrial drainage systems, with the Martian examples lacking small-scale streams feeding into the larger valleys. Because of the absence of small-scale streams in the Martian valley networks, it is thought that the valleys were carved primarily by ground water flow rather than by runoff of rain. Although liquid water is currently unstable on the surface of Mars, theoretical studies indicate that flowing groundwater might be able to form valley networks if the water flowed beneath a protective cover of ice. Alternatively, because the valley networks are confined to relatively old regions of Mars, their presence may indicate that Mars once possessed a warmer and wetter climate in its early history. 

Landslide in Valles Marineris

This image shows a close-up view of a landslide on the south wall of Valles Marineris. This landslide partially removed the rim of the crater that is on the plateau adjacent to Valles Marineris. Note the texture of the landslide deposit where it flowed across the floor of Valles Marineris. Several distinct layers can be seen in the walls of the trough. These layers may be regions of distinct chemical composition or mechanical properties in the Martian crust. 

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