July 14, 2008—A valley system known as Echus Chasma slashes through the surface of a Martian high plateau in an image released Monday taken by the Mars Express orbiter. The region may have been one of the largest water sources on early Mars and could have produced the deluge that created the Kasei Valles system of channels.

Echus Chasma is some 62 miles (100 kilometers) long and 6.2 miles (10 kilometers) wide. It cuts 2.5 miles (4 kilometers) deep into the surrounding plains. If the red planet once had liquid water, enormous waterfalls may have spilled over the rift's now-dry cliffs.

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