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NASA’s Curiosity rover found a series of 10 m (33 ft) high symmetrical gravel ridges – sedimentological evidence of ancient giant floods – in Gale Crater on Mars.
This artist’s impression shows what Mars looked like about 4 billion years ago. Image credit: M. Kornmesser / ESO.
“We identified megafloods for the first time using detailed sedimentological data observed by the Curiosity rover,” said Dr. Alberto G. Fairén, an astrobiologist in the Cornell University Department of Astronomy and the Spanish Centro de Astrobiología.
“The deposits left by the megafloods had not previously been identified with the orbiting data.”
As in the case of the Earth, the geological features, including the work of water and wind, were frozen in time on Mars about 4 billion years. These features convey processes that have shaped the surface of both planets in the past.
“This case includes the presence of gigantic wave-shaped features in the sedimentary layers of Gale Crater, often called megaripples or antidunes that are about 19m high and spaced about 137m (450ft) from each other,” he said. Professor Ezat Heydari, a researcher in the Department of Physics, Atmospheric Sciences and Geosciences at Jackson State University.
“Antidunes are indicative of megafloods flowing at the bottom of Gale Crater about 4 billion years ago, which are identical to features formed by the melting of ice on Earth about 2 million years ago.”
(A) The Curiosity Mastcam image mosaic acquired on Sol 646 (looking south-east) shows the Curiosity (HPU) exposure inside an impact crater; here the unit has a thickness of about 8 m and consists of undifferentiated conglomerate beds crossed with large clasts up to 20 cm; crossed beds indicate northward flow (to the right of the image). (B) and (C) are enlarged portions of areas (A) and show conglomerate cross-laminated; the yellow lines are traces of crossed beds. (D) Mosaic of Mastcam images acquired on Sol 631 (looking north-east); the picture shows a 60 m long cross bed in the 2-3 m high HPU; the cross-layered layer is truncated by layers of the Striated Unit (SU) with strong contact highlighted by a yellow dashed line; indicates the direction of flow to the north-east. Image credit: Malin Space Science Systems / NASA / JPL.
The most likely cause of the flooding of Mars was the melting of the ice caused by the heat generated by a large impact, which released carbon dioxide and methane from the planet’s frozen reservoirs.
Water vapor and the release of gases combined to produce a short period of hot and humid conditions on the Red Planet.
The condensation formed clouds of water vapor, which in turn created torrential rains, possibly all over the planet.
That water entered the Gale Crater, then combined with the water flowing down from Mount Sharp to produce gigantic flash floods that deposited the gravel ridges in the Hummocky Plains unit and the band formations of ridges and depressions in the striated unit.
“Early Mars was an extremely active planet from a geological point of view,” said Dr Fairén.
“The planet had the conditions necessary to support the presence of liquid water on the surface and on Earth, where there is water, there is life.”
“So early Mars was a habitable planet. Was it inhabited? This is a question that the upcoming Perseverance rover will help answer. “
The study appears in the journal Scientific reports.
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E. Heydari et al. 2020. Deposits from giant floods in Gale Crater, and their implications for the climate of the beginning of Mars. Ski Rep 10, 19099; doi: 10.1038 / s41598-020-75665-7
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