earths internal energy

• Igneous rocks are formed from the solidification of molten material, either magma or lava.
• heat is measured within the earth through mines and boreholes
• the interior of the earth is hot due to a process called accretion, gravitational attraction of material towards earth, the impacts of gpe were released as thermal energy, this heat has not escaped because the lithosphere is a good insulater
• the interior is also hot due to radioactive decay of isotopes like potassium, uranium and thorium that occur in the mantle and crust
• the outer core was made as siderophile elements sank towards the core and the loss of gpe was enough to melt them
• the change in state from molten outercore to solid inner core, this releases heat and the inner core grows by 0.5mm a year
• the main silicate minerals in the lithosphere do not conduct heat well so it traps heat in the mantle
• convection moves heat around the mantle
• advection is magma and hot water rising through the crust, the heat is carried by the movement of physical matter
• geotherm: a line that shows how temp changes with depth in our planet
• thermal heat flux: the rate of heat transfer per unit of time
• geothermal gradient: the increase in earths temp with depth
• the equation for geothermal gradient: $change in temperature/change in depth$