Editing Geophysics (section)

=== Heat flow ===
{{Main|Geothermal gradient}}
[[File:Convection-snapshot.png|thumb|upright=1.4|A model of [[thermal convection]] in the [[Earth's mantle]]. The thin red columns are [[mantle plumes]]. |alt=Pseudocolor image in vertical profile.]]
The Earth is cooling, and the resulting [[heat flow]] generates the Earth's magnetic field through the [[geodynamo]] and plate tectonics through [[mantle convection]].<ref name=Davies>{{harvnb|Davies|2001}}</ref> The main sources of heat are: primordial heat due to Earth's cooling and [[radioactivity]] in the planets upper crust.<ref>{{Cite web |title=What is "Heat Flow"? |url=https://www.smu.edu/dedman/academics/departments/Earth-Sciences/Research/GeothermalLab/DataMaps/GeothermalMapofNorthAmerica/What-is-Heat-Flow |access-date=2024-02-18 |website=www.smu.edu |language=en}}</ref> There is also some contributions from [[phase transitions]]. Heat is mostly carried to the surface by [[thermal convection]], although there are two thermal boundary layers – the [[core–mantle boundary]] and the [[lithosphere]] – in which heat is transported by [[Conduction (heat)|conduction]].<ref name=Fowler>{{harvnb|Fowler|2005}}</ref> Some heat is carried up from the bottom of the [[Mantle (geology)|mantle]] by [[mantle plumes]]. The heat flow at the Earth's surface is about {{math| 4.2 × 10<sup>13</sup> W}}, and it is a potential source of [[Geothermal energy|geothermal]] energy.<ref name=Pollack>{{harvnb|Pollack|Hurter|Johnson|1993}}</ref>