Magnetism occurs whenever electrically charged particles are in motion.
The Earth's molten core has electric currents flowing through it.

Paleomagnetism is the study of the Earth’s ancient magnetic field through the record of remanent magnetism preserved in rocks.
The directions of remanent magnetization are used to deduce the position of the Earth’s magnetic pole relative to the study location at the time when this magnetization was acquired.
Overview of Methods Superposition Stratigraphy Dendrochronology Radiocarbon C14 Radiometric Dating Methods Obsidian Hydration Dating Paleomagnetic/Archaeomagnetic Luminescence Dating Methods Amino Acid Racemization Fission-track Dating Ice Cores Varves Pollens Corals Cation Ratio Fluorine Dating Patination Oxidizable Carbon Ratio Electron Spin Resonance Cosmic-ray Exposure Dating This is an excellent overview of dating methodologies, and is a chapter in a textbook on Archaeology.
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To aid in the development of such a model, the emplacement ages of two kimberlite occurrences, K5 and K6 from the Buffalo Head Hills region of north central Alberta, and the ultramafic Mountain Lake body from northwestern Alberta were estimated using paleomagnetic methods.
Paleomagnetic pales obtained in our study do not differ statistically from the reference pales for late Mesozoic -Cenozoic for North America (Besse and Courtillot 2002).
The Earth's magnetic core is generally inclined at an 11 degree angle from the Earth's axis of rotation.
Therefore, the magnetic north pole is at approximately an 11 degree angle from the geographic north pole.
The Earth's magnetic north pole can change in orientation (from north to south . Paleomagnetic and archaeomagnetic dating rely on the fact that the Earth's.