you do not realise a high mantle temperature, and low silica flowing rock is consistent with a young earth geology model, indeed rapid exposure of mantle material to ocean waters covering a globe is sufficient to lower the temperature, and further the continued presence of the masses detected just above the earths core by seismic tomography is even more consistent, as by the mantle temperature even as it is now, those masses should not exist if they were even a million years old, even a couple of 10s of thousands of years is an absurd lifetime for masses to retain their solidity at that depth and temperature,