Subduction is a hypothesis.
But it also blatant nonsense. It is actually the lie that plate tectonics depends on, hence cannot be questioned at all.
But it is nonsense, however.
Subduction would assume thing, which violate simple logic.
For instance plate tectonics is based on the assumption, that Earth would NOT grow. That's why the obvious spreading needs something to balance that spreading and that is the alleged subduction.
But spreading zones are large and obvious and subduction zones far less and in most cases at the 'wrong' locations (not opposite to spreading zones).
To make that nonsense somehow plausible additional blunder is need and actually introduced into 'science'.
In effect pt assumes, that continents kind of 'swim' through the ozeans.
But that assumption is insane, because the ozeans are above plates, too, because if there were no plates beneath the ozeans, the water would boil instantly.
So, more or less the entire planet is covered with plates and many are thinner and are covered with water, what we call 'ozeans'.
Now the plates below the ozeans are still thick plates, even not as thinck as the continental plates.
Now the question: how would you move any plate at all, if the entire planet is covered with thick plates?
As a relatively good 'model' you could use a water melon.
The 'crust' of the watermelon is relatively stiff and has equivalent thickness (a little too thick, but that doesn't matter).
Now we take a sharp knife and cut the 'crust' into 'plates' and name them like the plates on our planet.
Now we have a 'planet', covered with 'plates' and could try to move the 'plates' around.
But there are two things, which would hinder the movement:
1) these 'plates' stick to the interior of the 'planet' 2) there is no place for movement, because in any dierections there are other plates.Same with tectonic plates:
1) they are extremly heavy, hot and half molten on the lower side and stick to the upper mantle 2) they cannot move, because any border line has actually a vertical depth of several ten kilometers, which would push against other plates, once you try to move them.Plates are also extremly rigid, because they are made of rock.
So, any movement would cause a collision and that not only in the middle of the moving direction, but also sideways, where also collisions could occur.
In effect the only option, that would actually allow spreading would be a growing planet.
TH
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