This is CBS, I Am The World. I'm John Bachelotel Mars episode in with David Livingston,

Doctor Space of the Space Show. And we are discussing the surface of Mars, the planet

Mars, the history of Mars, with a planetary geologist, a man who's helping us understand

events that happened 3.4 billion years ago, that accidentally on purpose fate being what

it is, Viking 1, the first NASA probed on the surface of Mars of great extent from 1976

landed in a place that allowed the professor and its colleagues to reason backwards to

events in the late Asperian period of Mars, which is a period that is known for lots of

volcanoes, lots of volcanic activity. But in this instance, it's about an ocean on the

northern hemisphere that the professor tells us had an ice sheet on top of it and there's

a crater in it. So David, I turn to you for a question for the professor.

Professor, I'm a little bit confused. Did the enormous flood channel, was that created

by the impact or was that their first or what, how did it end up being a flood?

That's actually a really good question. I'm really happy that you asked it. So the

flood channels of Creciplanesia, they are called outflow channels, in the Mars on the

literature. There is a reason why they are called outflow channels, because they actually

came from aquifers. I mean the floods that produced them came from chaotic terrain that we

think are collapsed aquifers. Now, the sequence of events would have been the following. So

you have massive, very ancient aquifers around the Creciplanesia Highlands. The aquifers

become unstable during the late Asperian period, they collapse and they release huge amounts

of water. The water, the floods, carve the outflow channels that extend into the northern

plains, unformed the ocean. Then later, poll strikes and superposes. It disrupts the

fluvial landscapes generated by these outflow channels. So the sequence would have been

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