This is an image of Mars.
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Image from: NASA
The Earliest History of Mars
The terrestrial planets formed about 4 Billion Years ago. As the process which formed them came to an end, the planets may have been left in either of the following two states:
- very warm, with a softer & pliable interior. The planet separates into layers, and the heavy iron falls to the center of the planet to form a core. There is probably abundant water on the surface. There is probably volcanic activity as well as plate tectonics driven by the heat from inside.
- cold and rocky, needing to be warmed from the inside before activity is seen on the surface. The planet never separates into layers, the heavy iron stays near the surface, and the planet never forms a core.
With Mars, the second case is probably more likely because we can see a lot of iron on the surface (it's red), and the core is very small.
Nevertheless, during this time, the surface continued to be bombarded by the remanent of planetary material available nearby which caused a great deal of heating near the surface of Mars. This heating was accompanied by hydrothermal activity, or circulation of water within the ground. These conditions are very favorable for certain forms of life. Continental drift may also have been possible at this early time.
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