catastrophism

thumb|The discoveries of different layers of fossils, such as those containing Palaeotherium and [[Anoplotherium (pictured), by Georges Cuvier led him to believe that series of catastrophic events wiped out worlds before the modern one.]] In geology, catastrophism is the theory that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow incremental changes, such as erosion, brought about all the Earth's geological features. The proponents of uniformitarianism held that the present was "the key to the past", and that all geological processes (such as erosion) throughout the past resembled those that can be observed today. Since the 19th-century disputes between catastrophists and uniformitarians, a more inclusive and integrated view of geologic events has developed, in which the scientific consensus accepts that some catastrophic events occurred in the geologic past, but regards these as extreme examples of explicable natural processes.

Proponents of catastrophism proposed that each geological epoch ended with violent and sudden natural catastrophes such as major floods and the rapid formation of major mountain chains. Plants and animals living in the parts of the world where such events occurred became extinct, to be replaced abruptly by the new forms whose fossils defined the geological strata. Some catastrophists attempted to relate at least one such change to the Biblical account of Noah's flood.