A snapshot of a canyon in Mars and a similar structure on Earth hints that the Red Planet's geology may be very familiar to Earthlings.
The canyon in this image is Echus Chasma, a gash cut through a high Martian plateau called Lunae Planum. Echus Chasma is huge, stretching 62 miles (100 kilometers) and reaching about 6 miles (10 kilometers) wide. The image was taken on Sept. 25, 2005, by the high-resolution stereo camera aboard the European Space Agency's (ESA) Mars Express, according to the ESA.
Echus Chasma contains clay minerals, which only form in the presence of water, making the canyon an important site for understanding Mars' wet past.
Intriguingly, Echus Chasma looks much like landforms right here on Earth — in Idaho, specifically, according to NASA's Earth Observatory, which released two comparison images today (April 29). One example is the Woody's Cove, a small canyon in south-central Idaho that looks much like Echus Chasma. (Woody's Cove is only about a quarter-mile (0.3 km) long, according to Earth Observatory.) [The 7 Most Mars-Like Places on Earth]
In December, California Institute of Technology researchers studied Woody's Cove and a nearby canyon, Stubby Canyon, at Idaho's Malad Gorge. They found that the rounded heads of these canyons — known as "amphitheater heads" — likely formed as a result of an enormous flood. The mega-flood would have caused extremely rapid erosion and contributed to the shape of the canyon heads, the researchers reported in December 2013 in the journal Proceedings of the National Academy of Sciences.
The formation of these canyons was long attributed to a slower, more subtle process, according to Caltech. Geologists believed that groundwater bubbling up from springs at the bottom of the canyon undercut the rocks at the canyon edge, eventually resulting in chunks of rock higher up sloughing off. But the 2013 study found no evidence of undercutting and no huge boulders on the canyon floor that would have fallen from the canyon walls. Scour marks at the top of the canyon point to a very large movement of water.
A similar reckoning with the data might need to take place on Mars.
"A very popular interpretation for the amphitheater-headed canyons on Mars is that groundwater seeps out of cracks at the base of the canyon headwalls and that no water ever went over the top," Caltech study leader Michael Lamb, a geologist, said in a 2013 statement.
But the findings in Utah throw that interpretation into question. If Echus Chasma formed like its Earthbound lookalikes, Mars may have once been a very wet place indeed.