Water on Mars!
And then there are the ancient river deposits.
One such feature of the Martian landscape, studied by Curiosity while it was at a small depression near its landing site called Yellowknife Bay, is an outcrop researchers dubbed Shaler.
Shaler is an example of cross-stratification, which comprises thin, inclined layers of sediment. Features resembling Shaler are commonly formed by rivers here on Earth; turbulent water creates "dunes" on the riverbed, which slowly migrate in the direction of the current.
"And these look exactly like the sort of features I’ve looked at on Earth formed by ancient rivers," Gupta added. "So we can tell that these outcrops are clear evidence for sustained water transport and dune migration. When they are preserved, they are recording minutes to hours of motion, and they’ve been preserved for millions to billions of years."
The water flows that produced the dunes probably occurred billions of years ago, Gupta said.
I think this is thrilling!