Palaeomagnetism

Palaeomagnetism is the study of the record of the Earth's magnetic field in rocks, sediments, and archaeological materials. It is a branch of geophysics that utilizes the remanent magnetism acquired by certain minerals when they form. When these materials cool below a certain temperature, known as the Curie temperature, or when they are deposited and compacted, the magnetic domains within them align with the prevailing magnetic field at that time and location. This alignment is then preserved as a permanent magnetization.

By analyzing the direction and intensity of this remanent magnetism in samples collected from different locations and of various ages, palaeomagnetists can reconstruct the history of the Earth's magnetic field. This history includes not only changes in the field's strength and direction but also the phenomenon of magnetic reversals, where the north and south magnetic poles have swapped places many times throughout geological history.

The data obtained from palaeomagnetic studies are crucial for several fields of science. It provides strong evidence for plate tectonics, allowing scientists to map the movement of continents over millions of years. It is also used for dating geological strata, correlating rock layers across different regions, and understanding the chronology of Earth's history. In archaeology, palaeomagnetism can help date ancient hearths and fired materials, providing insights into past human activities.