The waters of Mars

Traces in the rock: Beds of sandstone inclined to the south-west toward Mount Sharp and away from the Gale Crater rim on Mars. The beds are interpreted as the deposits of small deltas fed by rivers flowing down from the crater rim to the north and building out into a lake to the south, where Mount Sharp is now. Scientists say the mountain may have built up over time from lake sediments. — AFP photos

Gale Crater once held a vast long-lived lake, Curiosity rover finds.

Water is going “mainstream” on Mars. Nasa’s Curiosity rover has discovered evidence of a vast lake in Gale Crater that potentially lasted millions of years – findings that may contradict the idea that much of the planet’s water reserves were held only in ice or underground, and made only transient appearances on the surface.