7 ms·

Strange how Mars had a planetary-round flood but Earth didn't.

ChrisMarshallNY 6y ago
I'm not sure that's the case. I think there's been some times (like maybe pre-Devonian), where the Earth was pretty much Waterworld. There was a series of books that Terry Pratchett co-authored, called The Science of Discworld, where a bunch of wizards were creating a planet, and it went through a bunch of phases, punctuated by E.L.E. asteriod impacts. I think it was a fanciful chronicle of early Earth. Interesting books.
- IanCal 6y ago
  I avoided those books for a long time as I thought they were going to be made up explanations for how things worked in the Discworld. They're actually a wonderful set of stories and jumping off point for discussing a variety of topics. Heavily recommend them to people who may have been in the same position as me.
  - ZeroGravitas 6y ago
    Yes, they're a good mix of Pratchett content and well written popular science coverage of concepts. As well as the science ones there a Folklore of Discworld which could easily have been a throwaway novelty but was a great unsight into the real folklore that Pratchett references and lampoons.
rement 6y ago
Some scientist hypothesize that millions of years ago the Earth's surface completely froze over. It is called snowball earth [0]. [0] https://en.wikipedia.org/wiki/Snowball_Earth https://en.wikipedia.org/wiki/Snowball_Earth
- cultus 6y ago
  The geologic evidence for Snowball Earth (multiple ones, actually) is extremely strong. It is almost impossible to explain the re-emergence of banded iron formations without it. The hard part is explain is how photosynthetic life survived. The Slushball Earth hypothesis holds that there was a band of thin ice near the equator. This has some severe problems though. For one, it isn't climatologically stable. The oceans in SE were covered by "sea glaciers," which were floating glaciers thicker near the poles, which flowed to the equator. These flowed due to the weak hydrologic cycle, with ice experience net sublimation near the equator. These would have overridden any areas of thin or nonexistent ice. A hypothesis that is getting more traction is that narrow equatorial rift seas (like the Red Sea) would have prevented inflow of the sea glaciers enough for thin-ice refuges to exist. These kind of seas probably existed, because this was occurring as the supercontinent Rodinia was beginning to break up.
  - kwk1 6y ago
    > A hypothesis that is getting more traction is that narrow equatorial rift seas (like the Red Sea) would have prevented inflow of the sea glaciers enough for thin-ice refuges to exist. Wow, that makes imagining conditions on the Snowball Earth all the more fascinating, thank you.
grey_earthling 6y ago
75% of Earth's surface is still flooded :)
- Konohamaru 6y ago
  Geologists generally speaking don't know how the ocean emerged, but all agree it wasn't due to a catastrophic deluge.
  - eloff 6y ago
    At least after formation, but also likely again after the impact thought to produce the moon, all the surface was melted, so all the water was in the atmosphere and inside the Earth. When things cooled enough for liquid water to rain down and stay liquid, that must have been some deluge.

I'm not sure that's the case. I think there's been some times (like maybe pre-Devonian), where the Earth was pretty much Waterworld. There was a series of books that Terry Pratchett co-authored, called The Science of Discworld, where a bunch of wizards were creating a planet, and it went through a bunch of phases, punctuated by E.L.E. asteriod impacts. I think it was a fanciful chronicle of early Earth. Interesting books.

IanCal 6y ago
I avoided those books for a long time as I thought they were going to be made up explanations for how things worked in the Discworld. They're actually a wonderful set of stories and jumping off point for discussing a variety of topics. Heavily recommend them to people who may have been in the same position as me.
- ZeroGravitas 6y ago
  Yes, they're a good mix of Pratchett content and well written popular science coverage of concepts. As well as the science ones there a Folklore of Discworld which could easily have been a throwaway novelty but was a great unsight into the real folklore that Pratchett references and lampoons.

rement 6y ago

Some scientist hypothesize that millions of years ago the Earth's surface completely froze over. It is called snowball earth [0]. [0] https://en.wikipedia.org/wiki/Snowball_Earth https://en.wikipedia.org/wiki/Snowball_Earth

cultus 6y ago
The geologic evidence for Snowball Earth (multiple ones, actually) is extremely strong. It is almost impossible to explain the re-emergence of banded iron formations without it. The hard part is explain is how photosynthetic life survived. The Slushball Earth hypothesis holds that there was a band of thin ice near the equator. This has some severe problems though. For one, it isn't climatologically stable. The oceans in SE were covered by "sea glaciers," which were floating glaciers thicker near the poles, which flowed to the equator. These flowed due to the weak hydrologic cycle, with ice experience net sublimation near the equator. These would have overridden any areas of thin or nonexistent ice. A hypothesis that is getting more traction is that narrow equatorial rift seas (like the Red Sea) would have prevented inflow of the sea glaciers enough for thin-ice refuges to exist. These kind of seas probably existed, because this was occurring as the supercontinent Rodinia was beginning to break up.
- kwk1 6y ago
  > A hypothesis that is getting more traction is that narrow equatorial rift seas (like the Red Sea) would have prevented inflow of the sea glaciers enough for thin-ice refuges to exist. Wow, that makes imagining conditions on the Snowball Earth all the more fascinating, thank you.

grey_earthling 6y ago

75% of Earth's surface is still flooded :)

Konohamaru 6y ago
Geologists generally speaking don't know how the ocean emerged, but all agree it wasn't due to a catastrophic deluge.
- eloff 6y ago
  At least after formation, but also likely again after the impact thought to produce the moon, all the surface was melted, so all the water was in the atmosphere and inside the Earth. When things cooled enough for liquid water to rain down and stay liquid, that must have been some deluge.