Evidence of a flood following a flood indicates abundant water in early March

Mariner 4 was the first rover on Mars to land on the planet in 1965. Explorations continued, and over the past two decades, Sojourner, Spirit, Opportunity and Curiosity rovers have sent invaluable data back to scientists trying to interpret the surface and discover traces of past or present water.

Since landing on the "red planet" in August 2012, Curiosity Rover has traveled about twenty kilometers in the crater of Gale. The rover has examined about 400 meters of sedimentary rocks present in the crater, said Ezat Heydari of Jackson State University in Jackson, Mississippi, including rocks whose age is estimated at 3.7 to 4, 1 billion years (Noachian period).

Heydari and his colleagues used these images of sedimentary rocks to interpret the geological processes that occurred billions of years ago on Mars. He presents his findings Sunday at the annual meeting of the Geological Society of America in Indianapolis, Indiana.

In these 400 meters of rock, the researchers identified four different units representing different types of deposits, and Heydari said that "in my opinion, the deposits of all these packages involved water".

One of these packages, called Hummocky Plain Unit, is a conglomerate whose grains can reach a size of 20 centimeters. The Curiosity images showed ridges in the Hummocky Plain unit, filled with rounded pebbles and crossed layers up to 4 feet high, indicating that the deposit was made by moving water.

In addition, some images contain height information that can create a topographic profile of the surface, revealing the peak profiles. "These edges are asymmetrical," says Heydari. "In other words, they were formed by a directional current."

After viewing the images, Heydari immediately thought of the Channelized Scablands of Washington State. The crests of Mars are equidistant, he adds, adding that they are about twice as large as those of the Scablands. The ridges of Mars and Earth had similar characteristics, but it was only after seeing the cross-layers that Heydari concluded that the Mars deposits had been made by a large-scale flood.

Heydari notes that "with the help of comparisons with the rivers of the Earth, to create beds across 4 meters high, the running water would have had a depth of about 10 to 20 meters. "That's one of the reasons I say that these deposits are flood-related, rather than a shabby river," he says.

According to Heydari, the Noachian sedimentary rocks found in the Gale crater may have been deposited in an environment similar to that of the Pleistocene Earth (about 2 million years ago at 12,000 years ago), with global ice at large scale and catastrophic floods.

"On both planets, one hemisphere was covered with ice – the northern hemisphere on Earth, compared to the southern hemisphere on Mars – and the other hemisphere was hot," said Heydari. He adds that this comparison is important because it shows that the old Mars looks very similar to the Pleistocene Earth, where liquid water is stable and able to support life.

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More information:
Significance of Flood Depots in Gale Crater, Mars. Geological Society of America Abstracts with programs. Flight. 50, No. 6 DOI: 10.1130 / abs / 2018AM-319960, https://gsa.confex.com/gsa/2018AM/webprogram/Paper319960.html