Supervolcanoes ripped up early Mars
Mars may have had giant explosive volcanoes in its ancient past that spewed billions upon billions of tonnes of rock and ash into the sky.
Vast areas of collapsed ground in a region of the planet called Arabia Terra are their likely remains, believe Joe Michalski and Jacob Bleacher.
The two scientists report their findings in this week's Nature journal.
They say such supervolcanoes would have had a profound impact on the early evolution of Mars.
Joe Michalski told Roland Pease, on the BBC's Science In Action programme, what an eruption by one of these volcanoes would be like.
03 Oct 2013