Catastrophe

event causing sufficient damage to people, property or society;

recovery long and complex (ex. floods, tornadoes)

Principle of Catastrophism

All of the Earth's major features have been produced by a few great catastrophic events (popular in 17th and 18th centuries)

Principle of Uniformitarianism

The same physical processes active in the environment today have been operational throughout geologic time; "the present is the key to the past"