Answer:
heat from the decay of radioactive elements.
frictional heating, caused by denser core material sinking to the center of the planet
Explanation:
Answer:
The two sources of thermal energy in Earth's interior is radiogenic heat and primordial heat.
Explanation:
The radiogenic heat produced by the radioactive decay of isotopes in the mantle and crust, and the primordial heat left over from the formation of Earth.
