Which sphere experiences changes over time

the interactions among the spheres have changed the Earth system and the individual spheres. An interaction can take one of many forms. It can be a single event, such as the eruption of a volcano or a flood. It can be a temporary change, such as a cold snap that kills a fruit crop. Or it can be an ongoing, steady process, such as erosion. The idea that Earth is always changing, and that the forces of change at work now are the same as those in the past, is called uniformitarianism.