Hints: Earth December sedimentary rock

But even if there had been water, life doesn't start overnight. Even a simple microbe is the product of complex chemical systems that take millions of years to evolve. Had the water lasted long enough for life to form?
Well, when we look at the history of life on Earth, it appears to start very quickly, maybe a hundred million years. Now that seems like a long time, but for a planet that's short. So I would guess that if there was water on Mars for a couple of hundred million years, then life had a good shot at getting started there.
And soon they found evidence that water had been there for millions of years. It was all because of one very important picture. Sent back in December 2000, it was a vast formations of sedimentary rock. Sediment is basically made of sand, and could only have been deposited over millions of years by a huge body of water, like a lake or an ocean. It showed that there had not only been masses of water, but that it had been around easily long enough for life to form. The sediments on the surface are now dry and exposed.

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