Convulsionism

Also called catastrophic theory. It was put forward by French scholar Cuvier (1769-1832) in 1812. (1) Sudden, intense global upheaval within a short term. (2) Changes of organisms (including flora and fauna) on the earth are the results of many repeated catastrophes. Catastrophes appear repeatedly, and different organisms are created along with them. In the past, Catastrophism is thought to be totally wrong. However, development of geology finds that some geological event cannot be explained by Uniformitarianism. For instance, some scholars believe that climate changes, extinction of many creatures at late Mesozoic period, etc., have the nature of catastrophe.
 

Ordovician period - Silurian period mass extinction         Permian period mass extinction