Which term describes the theory that major changes in the Earth's crust during geological history have resulted chiefly from sudden violent and unusual events?

• A. Theory
• B. Uniformitarianism
• C. Catastrophism
• D. Plate tectonics

Answer: (C)

The idea being tested is that Earth's major crustal changes come mainly from sudden, violent events. This fits catastrophism, the view that abrupt disasters—such as floods, impacts, or large volcanic eruptions—have driven the most significant changes in Earth’s geology. It explains why geologists sometimes look for evidence of rapid, dramatic episodes in the rock record.

This contrasts with uniformitarianism, which holds that the same slow, observable processes operating today—erosion, sedimentation, uplift—have acted at roughly constant rates over long times. Plate tectonics describes the movement of large crustal plates and the interactions that shape the surface, but the term described by the prompt emphasizes sudden events rather than gradual change. So, catastrophism is the term that best matches the idea.