A very long time ago, a large amount of water is thought to have flowed on the surface of Mars – and the above image shows what scientists think is an ancient Martian river channel that has been buried by volcanic material.
The river was probably created by a massive release of groundwater and the image shows the main channel as well as islands that have been shaped by the flow. The river is part of the 1000 km-long Marte Vallis channel system, which is believed to have been carved out less than 500 million years ago.
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