spacetoday.net: Mars crater could be ancient supervolcano

Posted: Thu, Oct 3, 2013, 6:59 AM ET (1059 GMT)
Eden Patera crater on Mars (ESA)

A basin on the surface of Mars originally believed to be the remnant of an impact may instead be the remnant of a supervolcano that erupted early in the planet's history, scientists reported this week. The basin, known as Eden Patera, had been considered an impact crater, but scientists analyzing images of it did not find the raised rim or blankets of ejecta normally associated with impact craters. Other geologic features led scientists to suspect that this crater was actually a volcanic caldera. Eruptions of that volcano could have thrown large amounts of ash and other material into the atmosphere, which it could have remained for years, altering the planet's climate.