What caused the red sands of Mars?
Were the red sands of Mars caused by biological activities because when the levels of oxygen rose on Earth billions of years ago, large quantities of iron rusted out of the atmosphere, and that left iron oxide deposits in rocks. So could the same thing have happened to Mars?
We put this to Dr Matt Balme,Possibly, I think it's probably not the right reason though. I think the reason sands on Mars are red is really just due to a magnetite composition or ferrous iron mineral composition. You know, Mars may or may not have had an ocean. If it did have an ocean, it probably didn't exist for a very long period of time, relatively speaking, not like the Earth, which has been around for billions of years. So you know, we're loathe to rule anything out until we actually go there. I mean, that's one of the wonders of planetary science. There's an alternative answer to almost everything.