
Glaciers may have covered the entire planet twice - dnetesn
http://nautil.us/blog/glaciers-may-have-covered-the-entire-planettwice
======
cbkeller
May have been three times even: in addition to the two Neoproterozoic
"snowball earth" episodes they discuss here, there's also pretty decent
evidence for an even older (~2.2 Ga) Paleoproterozoic one [1]

I've worked a little bit on things relevant to this, previously discussed at
[https://news.ycombinator.com/item?id=18798130](https://news.ycombinator.com/item?id=18798130)

[1]
[https://www.pnas.org/content/102/32/11131.short](https://www.pnas.org/content/102/32/11131.short)

------
DrScump
This is just stupid misuse of terminology.

The Earth has been covered by _ice_ multiple times in prehistory, but it has
never been covered by _land_ (in fact, it's unlikely that even a _majority_ of
Earth's surface was above sea level).

Glaciers are strictly _overland_ formations.

~~~
ncmncm
If all the water is frozen, what does "sea level" even mean?

~~~
DrScump
It's never frozen all the way down (on Earth); only the surface layer freezes.

