I know I’m treading on non-observed, and therefore non-scientific speculative ground here, but I posit that if the Earth’s core were largely comprised of the elements models suggest, then it should have cooled due to conduction, convection, and radiation long ago.
I believe the Earth’s core is comprised of more thorium, uranium, and other radioactive elements than we currently understand to be there. This is where the sustained heating is coming from, this is what drives magma chambers and hot smokers. I recognize no fusion occurs in a body of Earth’s mass.
I also believe that plate tectonics could not function if the Earth were truly contracting as some suggest. There would be no room for slippage, only subduction.
Like biscuits rising in the oven, I think the Earth is ever so slightly expanding due to the radiative heat from the core, and new earth arises and fills the voids in the cracks between the plates, but not at all necessarily up to surface heights. Otherwise, I believe, the crust exposed core-side would simply be melted from underneath and there would be no plates, only a fused mass, and there would be no frictional force to move the plates exceeding the frictional force between the plates. If the Earth were truly contracting, the forces locking the plates together should be increasing, thus limiting slip, and there should only be subduction zones powered by the spreading of the mid-ocean ridge. If the Earth were contracting, the only exit for the increasing pressure from the mantle/core heat would be fissures and volcanoes. If the Earth were contracting, we should see a decrease in plate tectonics and earthquakes, and an increase in volcanism and hot smokers.
The only reason plates can move is of course (in my opinion) due to the frictional force between the plate and the upper mantle being greater than the frictional force between the plates themselves. The frictional force between the plates is being reduced by the slight separation caused by the slight expansion of the biscuit-Earth rising.
I know, I’m on unsupported scientific ground here. But Earth’s earth rising like a biscuit in an oven does account for our belief that early on there were mostly shallow oceans and not nearly as much land as today.
I have really no evidence at all for this belief, only a curiosity as to why the ocean floor extending from the mid-ocean ridge is so much younger than the ocean floor elsewhere. How to account for new earth while there is old earth, and apparently no zone where subduction is happening rapidly enough to swallow all the new earth being created around the globe into the small subduction zone?
It would seem to me that if the Earth were staying relatively the same size or contracting, there should be a very active subduction zone somewhere, and I’m not certain we’ve identified one.
I am not aware of any study that has tried to correlate the amount of earth subducting at the various subduction zones with the amount accreting from the mid-ocean ridge. This value should be negative if the Earth is contracting, and positive if the Earth is expanding.
Any help here would be appreciated.
I would like to present again for the reader’s consideration an accurate depiction of the Earth:
The above graph is true to scale, one pixel equals one kilometer. The blue pixels represent the average thickness of the crust under the oceans of 5-10 kilometers. The brown pixels represent the average thickness of the continental crust of 35-70 kilometers. The oceanic crust is properly represented as 70% of the surface.
As a different analogy, the reader is asked to consider what happens to a hard boiled egg left too long in the boiling water? The thin shell cracks and spreads, the volume of the egg having increased slightly.