Geodynamics refers to the processes by which mantle convection shapes and reshapes the Earth and other rocky planets. Its study includes plate tectonics, volcanism, the chemistry of lava and volcanic rocks, gravity and geomagnetic anomalies as well as seismic investigations into the structure of the mantle. Geodynamics is a subfield of geophysics dealing with dynamics of the Earth. It applies physics, chemistry and mathematics to the understanding of how mantle convection leads to plate tectonics and geologic phenomena such as seafloor spreading, mountain building, volcanoes, earthquakes, faulting and so on.