Ancient Martian Megaflood: Floods of Unimaginable Magnitude Once Washed Through Gale

Oblique view of Gale Crater, Mars, with vertical exaggeration. The image combines elevation data from the High Resolution Stereo Camera on the European Space Agency’s Mars Express orbiter, image data from the Context Camera on NASA’s Mars Reconnaissance Orbiter, and color information from Viking Orbiter imagery. Credit: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS

Field Geology at Mars’ Equator Points to Ancient Megaflood

Floods of unimaginable magnitude once washed through Gale Crater on Mars’ equator around 4 billion years ago – a finding that hints at the possibility that life may have existed there, according to data collected by NASA’s Curiosity rover and analyzed in joint project by scientists from Jackson State University, Cornell, the Jet Propulsion Laboratory and the University of Hawaii.

The research, “Deposits from Giant Floods in Gale Crater and Their Implications for the Climate of Early Mars,” was published on November 5, 2020, in Nature Scientific Reports.

The raging megaflood – likely touched off by the heat of a meteoritic impact, which unleashed ice stored on the Martian surface – set up gigantic ripples that are tell-tale geologic structures familiar to scientists on Earth.

“We identified megafloods for the first time using detailed sedimentological data observed by the rover Curiosity,” said co-author Alberto G. Fairén, a visiting astrobiologist in the College of Arts and Sciences. “Deposits left behind by megafloods had not been previously identified with orbiter data.”

As is the case on Earth, geological features including the work of water and wind have been frozen in time on Mars for about 4 billion years. These features convey processes that shaped the surface of both planets in the past.

This composite, false-color image of Mount Sharp inside Gale crater on Mars shows geologists a changing planetary environment. On Mars, the sky is not blue, but the image was made to resemble Earth so that scientists could distinguish stratification layers. Credit: NASA/JPL

This case includes the occurrence of giant wave-shaped features in sedimentary layers of Gale crater, often called “megaripples” or antidunes that are about 30-feet high and spaced about 450 feet apart, according to lead author Ezat Heydari, a professor of physics at Jackson State University.

The antidunes are indicative of flowing megafloods at the bottom of Mars’ Gale Crater about 4 billion years ago, which are identical to the features formed by melting ice on Earth about 2 million years ago, Heydari said.

The most likely cause of the Mars flooding was the melting of ice from heat generated by a large impact, which released carbon dioxide and methane from the planet’s frozen reservoirs. The water vapor and release of gases combined to produce a short period of warm and wet conditions on the red planet.

Condensation formed water vapor clouds, which in turn created torrential rain, possibly planetwide. That water entered Gale Crater, then combined with water coming down from Mount Sharp (in Gale Crater) to produce gigantic flash floods that deposited the gravel ridges in the Hummocky Plains Unit and the ridge-and-trough band…