Discuss the relationship between magnetism and the formation of magmatic rocks, including the processes involved and the geophysical implications of magnetic minerals in Earth's crust. (100 words)

Magnetism and the formation of magmatic rocks are interconnected. During the cooling process of magma, magnetic minerals like magnetite align themselves with Earth's magnetic field, forming magmatic rocks. This process, known as thermoremanent magnetization, leaves a permanent record of the Earth's magnetic field at the time of rock formation. These magnetic signatures in the Earth's crust provide valuable geophysical data, helping scientists understand past geomagnetic field changes and tectonic plate movements. Therefore, the presence of magnetic minerals in the Earth's crust is crucial for studying Earth's geological history.