<Li> Glaciology covers the icy parts of the Earth (or cryosphere). </Li> <Li> Atmospheric sciences cover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere (about 1000 km). Major subdisciplines include meteorology, climatology, atmospheric chemistry, and atmospheric physics . </Li> <P> Plate tectonics, mountain ranges, volcanoes, and earthquakes are geological phenomena that can be explained in terms of physical and chemical processes in the Earth's crust . </P> <P> Beneath the Earth's crust lies the mantle which is heated by the radioactive decay of heavy elements . The mantle is not quite solid and consists of magma which is in a state of semi-perpetual convection . This convection process causes the lithospheric plates to move, albeit slowly . The resulting process is known as plate tectonics . </P>

2. what is an environmental sphere or earth system sphere