○○○
Mantle plumes are not rapidly rising jets of magma. Instead, they are broad upwellings – thousands of kilometers across – of magma and hot rock.
Surface plates, their motions, and their return to the mantle via subduction control mantle dynamics and heterogeneity. Ultimately, it is the cooling of the Earth, modulated by internal heating, that provides the energy for convection. ~ Don Anderson & American marine geologist James Natland
Little violent mixing of materials occurs deep within Earth. Subducted volcanic rock may travel through the mantle and resurface, largely intact, after billions of years. The deep mantle is a graveyard of ancient tectonic slabs.
From planetary wear and tear over the course of billions of years, rocks and minerals ground to a powder on the surface, mixing with moisture and microbes to become dirt. Life was well on its way by the time dirt was young.
