My understanding is that the sea floor is almost uniformly basaltic rock, whereas continental crust is a distinctly different type of rock.
Yep, I was reading about the difference in the rock from the sea floor away from the Mid Atlantic ridge relative to the rock at the Mid Atlantic ridge, and the differences are so small that one can call me wrong for saying they are different.
It's looking like the theory of alternating bands based on the previous band is busted unless I can come up with data consistent with the idea
It is the density difference between the two types of crust (continental and oceanic) that leads to oceanic crust always subducting under continental when they converge. The explanation for many mountain ranges is that two plates of continental crust converged, and for either one of them to subduct under the other would require “low density” continental crust to go deep into higher density rock in the mantle. Instead, the two converging continental plates slowly ram into each other and cause folding and upthrusting of the continental rocks, forming mountains. The Himalayas are one of the more recent mountain ranges so formed, by India pushing into the southern side of Asia.
This is the reason for looking for a different explanation. The energy required to push the oceanic crust under continental crust (to say nothing of continental crust under continental crust) is just too great for the mechanism of plate tectonics to do it. The only real way to get what we see today is for the crust to get up some momentum.
And there's more. The sea floor away from the bands doesn't follow a particular magnetic direction as it should. And even more damning, the direction of the field inside the bands themselves, deeper down, should be relatively even, but it's not.
Does that prove the hydroplate theory? No, but we have to find something that can actually account for the facts we see today. Plate tectonics isn't it.
But you bring to mind a question I have not entertained, and would be interested in seeing if anyone has an answer for. All of the oceanic crust under the Atlantic is dated at 200 million years or so or less. And I presume, at some time much father back, the seafloor of the Pacific was similarly formed by seafloor spreading. Then wouldn’t essentially each segment of the Pacific Ocean floor also show magnetic polarization for the same reason the Atlantic does?
That's just one of the many anomalies that shows plate tectonics is wrong. Something else happened.
And further, the more I look into the idea that magnetic field of one band drives the magnetic field of the next is looking less and less likely as DS has poked some holes in the theory that I can't answer so far.
Problem is, the facts simply don't support a reversing dipole. We have one fact, the bands in the Atlantic, that is supposed to support a reversing field, but there is something else that has to be going on. It wasn't reversals.
