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I'm confused by this. When I was blogging about life on Mars[1] I was using a date for the emergence of fresh water on Earth of 4.4 billion years ago(bya)[2].

I'm confused by this. When I was blogging about life on Mars[1] I was using a date for the emergence of fresh water on Earth of 4.4 billion years ago(bya)[2]. But this article says the date has been pushed back from 3.5 bya to 4.0 bya. But reading carefully, it looks like by "fresh water" they means water on land aka rain, not just the existence of seas. [1]https://hopefullyintersting.blogspot.com/2019/04/how-likely-is-it-that-there-was-life-on.html https://hopefullyintersting.blogspot.com/2019/04/how-likely-... [2]https://en.wikipedia.org/wiki/History_of_Earth https://en.wikipedia.org/wiki/History_of_Earth

OJFord 2y ago
'Fresh water' always means as opposed to salt/sea water. 'Fresh water fishing', etc. (I'm not sure where you draw the line in rivers though)
- Symmetry 2y ago
  It's just that I have a hard time imagining that there were seas without any rain occurring for hundreds of millions of years so it didn't occur to me that these could be separate questions. And most of the comments here seem to be conflating them as well.
- didgetmaster 2y ago
  I also have a hard time understanding how they differentiate between salt water and fresh water so long ago. It seems like the salinity of the oceans has changed over time. The first seas might have been quite fresh as compared to the ocean today (or even more salty).