By Kerry Sheridan, AFP
MIAMI–A mountain on Mars may have built up over time from lake sediments, according to NASA scientists who have been studying observations from the Curiosity rover scouring the Red Planet. The latest analysis is based on rocks discovered at the lower edges of Mount Sharp, which is located, rather oddly, in the midst of a crater on Earth’s neighboring planet.
��Gale Crater had a large lake filling the bottom of the 155-kilometer-across crater, perhaps even a series of lakes,�� said Michael Meyer, Mars Exploration Program lead scientist at NASA. ��This lake was large enough that it could have lasted millions of years, sufficient time for life to get started and thrive, sufficient time for lake sediments to build up and form Mount Sharp.�� While scientists are still not sure how long Mars was wet for any given spell through history, they were stunned to find slanted rocks and soil that point to the existence of a lake bed in the crater, said Curiosity project scientist John Grotzinger of the California Institute of Technology. Known as inclined strata, this kind of geological formation is key for understanding how a planet formed but is hard to find distinct examples of, even on Earth, he told reporters. ��When we saw the inclined strata and they were dipping toward Mount Sharp that was really a great surprise,�� he said. Curiosity’s pictures and data collected from the Martian soil in the lowest sedimentary layers of Mount Sharp, which reaches a height of about three miles (five kilometers), has helped scientists see the remnants of how rivers once carried sand and silt to the lake, depositing sediment at the mouth of the river. This process would have repeated itself again and again to form a delta.