New compelling evidence suggests Mars was covered in river deltas and lakes

Compounding the intrigue from last month's water-on-Mars reveal, a new set of evidence uncovered by the Curiosity rover furthers the Martian mystery, suggesting that the Red Planet was once covered in river deltas and lakes, and may have even supported life.

Such theories are not new in and of themselves, but the latest batch of data substantiates the role that water has played in shaping Mars' geological history by exposing the means through which it may have been sustained for longer periods of time (long enough for life to have eventually sprung). The new answer to that riddle lies in impact craters.

Using Curiosity's power of observation by proxy, NASA's John Grotzinger and his team at the Mars Science Laboratory studied the sedimentary deposits along Mars' basin surfaces, called clinoforms, within the Gale Crater and discovered the basin's surface had risen over time in a process geologists called aggradation.

This implies that as Gale Crater's northern crater wall and rim eroded, gravel and sand must've been transported downward by shallow liquid streams. After long periods of time, the stream deposits moved increasingly closer to the crater's interior, eventually transforming into finer grains downstream just like ancient river deltas on Earth.

But in this case, the deltas form the boundary of an ancient Martian lake where fine, mud-sized sediments accumulated over the course of anywhere between 10,000 to 10,000,000 years; meaning, the lakes must've been fueled by a common groundwater table. (The age estimation was determined by comparing the Martian sediment specimens to physically similar depositional systems on Earth, for which there is a radiometric dating.)

 “These estimates are imprecise, order-of-magnitude in their quality,” explained California Institute of Technology geobiologist Woodward W. Fischer to Gizmodo. “But the important thing is that we can, beyond a single snapshot in time, identify a lake on Mars to recognize that these systems were sufficiently long lived that they left a strong fingerprint in the form of a thick package of sedimentary rocks.”

Whether or not the lakes were able to sustain life remains a mystery, but the belief that they remained stable for only 100 to 10,000 years at a time, suggests otherwise.

Source: Gizmodo