What is the term for the record of past changes in Earth's magnetic field as documented in geological materials?

The term for the record of past changes in Earth's magnetic field as documented in geological materials is referred to as paleomagnetism. This field of study involves analyzing the magnetic properties of rocks and sediments to understand how Earth's magnetic field has shifted over geological time.

Paleomagnetism allows scientists to reconstruct the historical movements of tectonic plates and provides crucial insights into plate tectonics, continental drift, and the geologic history of regions. By examining the orientation of magnetic minerals within rocks, researchers can infer the direction and intensity of the Earth's magnetic field when those rocks were formed, essentially acting as a time capsule of magnetic information.

In contrast, geomagnetism pertains generally to the study of the magnetic field of the Earth itself and does not specifically focus on geological records. Chronostratigraphy is a branch of stratigraphy that deals with the age and time relationships of rock strata, while tectonophysics involves the study of physical processes and properties related to tectonic plates and their movements, not directly concerning the magnetic record. Therefore, paleomagnetism is the specific term that captures the essence of the question about Earth's historical magnetic changes documented in geological materials.