Hills and a rift valley in Caralis Chaos
Hills and a rift valley in Caralis Chaos
These mounds in the Caralis Chaos region are probably the remains of very old deposits in what was once Lake Eridania, which covered an area of over one million square kilometres in the southern Martian highlands more than three and a half billion years ago. When the lake dried up, the material broke up and was subsequently further eroded by the wind. Later, the tectonic faults of the Sirenum Fossae ('the trenches of the sirens') overlay the landscape and cut through the hilly field. In the upper-right quadrant, a wrinkle ridge – formed when still malleable lava is compressed by lava flowing after it – extends perpendicular to this tectonic rift valley.
