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Mantle Dynamics

Moving plates and rising plumes . . .

The earth’s mantle is in slow motion, and the best-known manifestation of this is plate tectonics, which is the main internal process driving geological change in the earth’s crust. Mantle plumes also affect the earth’s surface: we think they are responsible for volcanic hotspots like Hawaii and Iceland.

. . . are kinds of convection

The motions of the plates and plumes are forms of convection in the mantle. Convection is driven by thermal boundary layers. In the earth’s mantle, the tectonic plates comprise the upper thermal boundary layer that sinks (subducts) because it is cooler and denser than the mantle interior. We think plumes are rising from a deep thermal boundary layer, possibly at the bottom of the mantle, that is hot and therefore buoyant.

This subject is covered in my book Dynamic Earth: Plates, Plumes and Mantle Convection.

Notes: Last modified: Wed, 19 Dec 2001