|Above: No, I'm not getting paid by Lego. It's just my way of sending a subtle hint to Santa...|
But recently the Curiosity Mars robot has found some things out about Gale crater on Mars that make it seem very likely there were not only streams but a lake there. The water seems to have come and gone. Curiosity Rover's Chief Scientist John Grotzinger described it as:
" [Not] just a single lake that stood for millions of years, but rather a system of alluvial fans, deltas and lakes and dry deserts that alternated probably for millions if not tens of millions of years as a connected system."
|Above: At present the water is definately going through a 'gone' phase....|