1. Explain Catastrophism (talk about the main characteristics - time, force, etc.). Catastrophism is referred to that the theory, which underpinned the fact pertinent to the changes that earth’s crust experienced in the era of geological history. This paved the way for sudden violent and unusual events. 2. Explain Uniformitarianism (same). Uniformitarianism is the theory which shed light on the fact that that changes which the earth's crust have confronted during geological history is a result from the action of continuous and uniform processes.