Actualism

A modern theory studying earth science. It accepts the basic premise of uniformitarianism and believes that during the whole period of earth history, the physical and chemical laws are unchanged, but the velocity and intensity which leads to results of geological processes may have changed greatly; some important and general geological events are actually catastrophic, for instance, earthquake and ice age. In addition, because the atmosphere, hydrosphere and lithosphere of earth are constantly changing during the lengthy historical period, during the process of evolution, the geological processes taking place on the earth or within the earth, relatively speaking, do change significantly over time.