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Ancient Ocean that covered 1/3 of Mars with Water, A new study conducted by University of Colorado at Boulder scientists.
ElkGroveDan
post Aug 20 2013, 04:33 PM
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QUOTE (RichforMars @ Aug 20 2013, 06:35 AM) *
And at this particular time in Martian history, how was reality on the planet we live on?


Reality on Earth? It was tangible but alas there was no one around to quantify it.


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centsworth_II
post Aug 20 2013, 05:53 PM
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QUOTE (RichforMars @ Aug 20 2013, 09:35 AM) *
And at this particular time in Martian history, how was reality on the planet we live on?
There are so many theories about how Earth was and how Mars was 3.5 to 4 billion years ago that I don't think we can know now on which planet oceans formed first. But I would guess that oceans likely existed on both planets at the same time at some point.

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nprev
post Aug 20 2013, 09:00 PM
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There's some evidence (D/H ratio, I think) that Venus once had oceans as well, BTW.

But, machts nicht. If Mars OR Venus indeed did have oceans there's just no way to positively tell if they coexisted with those of the Earth, really. Terrestrial geological evidence from that era is at best fragmentary; the LHB was beating the hell out of the entire inner Solar System for a lot of that time.



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serpens
post Aug 21 2013, 11:02 PM
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The evidence is fragmentary yes, but compelling for continental crusts and oceans at 4.4 Mya ago (detrial zircons - Yilgarn Craton, Western Australia). At that stage Earth was just a baby and the LHB was just getting into stride. There is no certainty as to the LHB time scale or the impact intensity distribution over the period, but given the evidence from the moon and Mars for hefty impactors a cycle of ocean vaporisation and condensation, for both Earth and Mars seems more likely than not.
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Chmee
post Aug 22 2013, 05:18 PM
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Strange to think that at one point Venus, Earth, and Mars, may have all had oceans at the same time. Three planets who may have started similarly, but have diverged dramatically since then. Also, given how new the surface of Venus is (i.e. 100 million years old?), perhaps its ocean lasted until relatively recently (in geologic terms). Maybe less then a billion years ago the oceans evaporated, than the plate tectonics stopped, and than the surface got covered in magma?
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elakdawalla
post Aug 22 2013, 05:52 PM
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Regarding Venus, it's better to assume that we are *not* living in a special time in its history. The simplest explanation for its youthful surface age is of a stagnant lid with periodic overturn -- every several hundred million years the cold lithosphere (which is denser than the hot stuff below it) founders and sinks into the mantle, producing a global paroxysm of volcanic activity that wanes and then quiets for a long time until it all happens again. This isn't the only possible explanation, of course, but you have to make a very strong case for an ad-hoc explanation before you can convince people that the uniformitarian explanation is false. This is an odd duck though, a uniform process of repeated catastrophes. I wonder what Hutton would think smile.gif


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serpens
post Dec 10 2013, 10:21 PM
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Well Curiosity seems to have confirmed that there was significant water during the Hesperian lasting millions to tens of millions of years. This is clear empirical evidence of a warmer, wetter Mars with neutral pH water.
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