Archaeomagnetic dating problems
The Earth's molten core has electric currents flowing through it.
As the earth rotates, these electric currents produce a magnetic field that extends outward into space.
They now point to the location of magnetic north at the time the firepit is being heated.
When the firepit cools the iron particles in the hardened clay keep this thermoremanent magnetization.
After World War II, geologists developed the paleomagnetic dating technique to measure the movements of the magnetic north pole over geologic time. Robert Dubois introduced this new absolute dating technique to archaeology as archaeomagnetic dating.
Magnetism occurs whenever electrically charged particles are in motion.
Directional dating can sometimes be as good as ±25 years.
Magnetic reversal stratigraphy has been useful in dating hominid sites for paleoanthropologists, with precisions of about ±0.01 Ma, or 10 ka.
Besides reviewing the basic principles of these methods, this article describes a number of applications, emphasizing explication of the method and solution of particular archaeological problems.
The Earth's magnetic north pole can change in orientation (from north to south and south to north), and has many times over the millions of years that this planet has existed.
The term that refers to changes in the Earth's magnetic field in the past is paleomagnetism.