How does the mantle convection hypothesis explain plate movements at divergent boundaries and subduction bound?
Mantle convection is like a pot of boiling water, but on a massive scale, and using an incredibly viscous plastic-molten medium that doesn’t move fast… at all. But at divergent boundaries, two convection cells that is going up meet, and that forces hot, less-dense magma to rise, pushing the plates away from each other. Further, the convective forces “grab” the plates and through friction help to pull them apart (though the field of geology is still a bit “out” on the mechanism of that occurrence). At a convergent/subduction boundary, the opposite happens. The crust is cold and dense, the mantle magma is on the “down” side of the convection cell, so the cooler sinking magma pulls the plate, and similar to the divergent boundary, the convection cell grabs the plate and pulls it along and down through frictional forces. If you make a simple two-dimensional drawing, it is pretty simple. But there’s a link below to an already drawn, drawing.
