NASA's Mars Reconnaissance Orbiter (MRO) has snapped photos of the Melas Basin, which researchers believe was once the location of a 1,300-foot-deep lake when Mars was a watery world billions of years ago. In the MRO image, "a group of steeply inclined light-toned layers is bounded above and below by unconformities (sudden or irregular changes from one deposit to another)," according to the NASA statement that accompanied the released image. The unconformities and layers likely resulted from materials being deposited on the lake floor by a river or river delta that flowed into the basin. "The layered deposits in Melas Basin may have been deposited during the growth of a delta complex," NASA said in the statement. "This depositional sequence likely represents a period where materials were being deposited on the floor of a lake or running river." Data from the MRO and NASA's Curiosity Rover suggests that when Mars was but a baby world, it was covered in a shallow layer of liquid water,