Curiosity from NASA’s For the last year, the Mars rover has been moving through an area that transitions from a clay-rich region to one that is rich in a salty mineral called sulphate. The transition zone is proving to be scientifically instructive as well, while the research team first focused on the clay-rich region and the sulfate-laden one for the data each may give regarding Mars’ wet history.This transition might serve as a record of a significant change in Mars’ climate that occurred billions of years ago but that scientists are only now starting to understand.
At one time, lakes and streams swept across Gale Crater, depositing material at the base of Mount Sharp, the 3-mile-tall peak whose foothills Curiosity has been climbing since 2014. At that time, the clay minerals developed. Curiosity’s observations in the transition zone higher up the mountain reveal that the streams reduced to trickles and sand dunes developed over the lake deposits.
This region also stands out for its distinctive geologic characteristics. The hills in the area probably started out as enormous, wind-swept sand dunes in a dry climate, eventually solidifying into granite. Other sediments transported by water and maybe deposited in ponds or little streams that formerly meandered amid the dunes are scattered among the fragments of these dunes. These sediments now resemble flaky layer stacks that are resistant to erosion, such as one known as “The Prow.”