[SunkenCiv]

Thanks Swordmaker for the topic.

[Eastbound]

"Atmospheres and surface material have been lifted from one body and fallen back or have been dumped on another."

And/or, as conjectured by Sitchin in 1976 ("12th Planet" pg 231, describing the collision of Nibiru (Marduk) and Tiamat:

'During that collision, the life-bearing soil and air of the Twelfth Planet "seeded" Earth, giving it the biological and complex early forms of life for whose early appearance there is no other explanation.'