The lithosphere has been broken up into moving plates that contain the world's continents and oceans. Below the lithosphere lies a relatively narrow, mobile zone in the mantle called the asthenosphere which is composed of hot, semi-solid material which can soften and flow after being subjected to high temperatures and pressure over time. Geology is the study on the Earth and its environment. Studies of the solid Earth, its shape, composition and physical properties, are the subjects of several disciplines. Geodesy is concerned with the shape of the Earth, its gravity field and the changes in the shape of the Earth brought about by tidal and tectonic forces.
Seismology is the study of earthquakes and related phenomena.
By monitoring seismic waves, scientists are able to study the physical properties of the interior of the Earth. Volcanology is the study of volcanoes, their origin, behavior and mode of occurrence. Geomagnetism and paleomagnetism have to do with the nature of Earth's magnetic field over geologic time. Studying these fields have made it possible to measure continental drift and to devise a geologic time scale for such event.