Earth, Our Environment - Class Notes
Chapter 2, Earth: Origin and Composition - 07
Earth's Internal Heat
The Earth is a heat engine - and is cooling, but it hasn't really cooled too much during geologic time, only about 1000 degrees.
[Study Figure 2.27 on page 41 of the text]
The two primary source of Earth's are:
- Primordial heat left over from the time of accretion and the separation of iron into the core.
- Radioactive heat from the decay of one element into another (a change in the atomic nucleus) .
The main heat producing elements in Earth are
Uranium, Thorium, and Potassium
Unlike the nuclear power in the Sun (fusion), these elements break down by fission - the breaking apart of the nucleus.
- Inner Core Freezing? Crystallization of the inner core is another potential source of heat, although the details are speculative.
[ Study Figure 1.16 from Text ]
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Prepared by: Chuck Ammon
cammon@geosc.psu.edu
February 1997