Earth's internal heat is thermal energy generated from radioactive decay and continual heat loss from Earth's formation.[2] Temperatures at the core–mantle boundary may reach over 4000 °C (7,200 °F).[3] The high temperature and pressure in Earth's interior cause some rock to melt and solid mantle to behave plastically, resulting in portions of mantle convecting upward since it is lighter than the surrounding rock. Rock and water is heated in the crust, sometimes up to 370 °C (700 °F).[4]