There was an old hypothesis that the Pacific Ocean basin is what the Moon came out of.
I kind of like this hypothesis in that it skirts the truth but is completely crazy.
I assume the originator was unfamiliar with (or denies) continental drift - at the very least.
It must be a very complex intellectual milieu to even think to advocate that decidedly minority opinion.
I was taught that in grade school long ago. I’d forgotten whose idea it was and had to look it up: George Darwin in 1879. Continental drift had not been worked out yet. Before Apollo 11, nobody knew the age of the moon. But I did notice that one of the Theia blobs in the lower mantle was under the Pacific and the other one half the world around under Africa.
In 1968 I was 9 and in 4th grade. I had a subscription to Science News and when I read that Jack Oliver had proved continental drift, it blew my little mind. The very next day after school, I dragged one of my school chums to my house to show him the news, like “Isn’t that the coolest thing ever?”* He must have thought I was crazy. But it charged me up with enthusiasm for geology.
*ETA: On second thought, I could have simply brought the magazine to school and showed lots of kids. I don’t know why I didn’t think of that at the time.
Yes; the Fission Theory, now discredited.
This is the now discredited hypothesis that an ancient, rapidly spinning Earth expelled a piece of its mass.[22][24] This was first proposed by George Darwin (son of the famous biologist Charles Darwin) in 1879[25] and retained some popularity until Apollo.[22] The Austrian geologist Otto Ampferer in 1925 also suggested the emerging of the Moon as cause for continental drift.[26]
It was proposed that the Pacific Ocean represented the scar of this event.[22] Today it is known that the oceanic crust that makes up this ocean basin is relatively young, about 200 million years old or less, whereas the Moon is much older. The Moon does not consist of oceanic crust but of mantle material, which originated inside the proto-Earth in the Precambrian.
Not really relevant. The tectonic plates are essentially ‘floating’ on top of the mantle so their position now isn’t related to their position 4.5 billion years ago. Neither the Pacific nor Africa existed, then. I mean, neither did the current plates they’re made of, or the continental crust that forms the core of the continents, either, for that matter.
At the time immediately before the collision, Earth likely made Mustafar look like Hoth.
Here’s a best guess of what plate tectonic movements looked like over the last billion years. (Beyond that, simulations is basically handwaving around a few sections of nearly primordial crust.) Notice the emergence of multiple new plates in the mid-Pacific, and the severing of multiple plates in what is now the Atlantic Ocean.
Stranger
The mantle itself is moving as well. You can’t really point at a spot and say where it was a billion years ago because not only has everything moved, it’s not all moved the same way so the concept doesn’t really have meaning.
A hotspot like the Hawaiian chain is a feature of the mantle that holds still while the crust is skidding over it.
Earth’s mantle is fairly plastic but undergoes continuous convective motion which is what helps drive plate tectonics. Kaua’i, the “grandaddy of Hawai’ian islands”, is only about 5.1 My old, which is a breath in geological time. Even the oldest seamounts of the Hawaiian-Emperor chain is only about 80 My. Why there is a volcanic hotspot beneath the Hawaiian-Emperor chain is unknown but it is caused by a diapir (an upflow of hot material from the more ductile lower mantle up through upper mantle and intruding into and sometimes through the crust). Why they appear and how they evolve over time is a large area of investigation in geophysics and geodynamics.
Stranger
Yep, the mantle’s convection cells drive continental drift. That’s why I said the hotspot is a feature of the mantle. It shows some kind of stability over time relative to the crust even though the mantle itself is in motion. What makes the heat rise right there: Good question. TBD.
And if I’m not mistaken, the direction of motion of the material in the convective cells reverses direction from time to time, making determination of “the same place” even less meaningful