Paleomagnetism

What is paleomagnetism?

Paleomagnetism is the branch of geophysics and geology that studies the Earth’s ancient magnetic field as recorded in rocks.

It allows us to reconstruct continental movements, tectonic rotations, mountain range formation, continental drift, and changes in the Earth’s magnetic field over geological time.

How is magnetism recorded?

Some magnetic minerals, especially magnetite and hematite, can align with the Earth’s magnetic field as the rock forms or cools. That magnetism becomes “frozen” in the rock.

In summary, as magma cools:

• Magnetic minerals align with the Earth’s magnetic field
• As they solidify, they retain that orientation
• Millions of years later, it can be measured in a laboratory

What information does it provide?

Paleomagnetism allows us to determine ancient latitude (where a rock was when it formed); tectonic rotations (whether a geological block rotated over time); plate movement (how the continents shifted); and magnetic reversals (when the magnetic north and south poles reversed)

Equipment such as magnetometers, demagnetization furnaces, and AF demagnetization are used.