Dating lava flows for paleomagnetic Telugusexchats
When lava and clay are heated, or lake and ocean sediments settle through the water, they acquire a magnetization parallel to the Earth's magnetic field.
This tells the geologist the orientation of the magnetic pole when the rock was hot.
This process is called thermoremanent magnetization in the case of lava and clay, and depositional remanent magnetization in the case of lake and ocean sediments.
In addition to changing in orientation, the magnetic north pole also wanders around the geographic north pole.
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.
By using another dating method (dendrochonology, radiocarbon dating) to obtain the absolute date of an archaeological feature (such as a hearth), and measuring the direction of magnetism and wander in the clay today, it is possible to determine the location of the magnetic north pole at the time this clay was last fired.