Paleomagnetism as a means of dating geological events parlin dating
Rocks from hot liquid magma (see lava), or even minerals made up of crystals that grow at low temperatures, can acquire magnetization.
Also, when magnetized minerals become disaggregated from their parent rocks by erosion and are carried into a basin, they will tend to align themselves parallel to the earth's magnetic field as they settle in still water.
Another type of stable remanent magnetization is chemical remanent magnetization (CRM), which arises during the growth of ferromagnetic grains in a magnetic field.
If the methods of geochronology give us the age of a rock, we thereby know when the rock was magnetized.
This knowledge is important for the study of the variation of the geomagnetic field in time.
Viscous remanent magnetization (VRM) arises during the prolonged action of a magnetic field on a rock and is a result of thermal activation and diffusion processes.
Detrital remanent magnetization (DRM) arises in sedimentary rocks when magnetic grains that already possess TRM or CRM are eroded from crystalline rocks.