What is the term for the idea that geologic processes have remained constant throughout Earth's history?

The concept of uniformitarianism is fundamentally linked to geological processes and is critical in understanding Earth's history. This principle posits that the natural processes observed today, such as erosion, sedimentation, and volcanic activity, have operated consistently over geologic time. This allows scientists to use current observable phenomena to interpret past geological events.

Uniformitarianism contrasts with the idea of catastrophism, which attributes significant changes in the Earth's geology to rare, large-scale events like asteroid impacts or massive volcanic eruptions. By adhering to uniformitarianism, researchers can build a more continuous narrative regarding the Earth's geological evolution, emphasizing gradual change over time rather than abrupt shifts. This principle was notably advanced by geologist James Hutton in the 18th century and further popularized by Charles Lyell in the 19th century, establishing a framework for modern geology and influencing related fields such as paleontology.

The other terms listed have distinct definitions that do not pertain directly to geologic time. Microevolution refers to small-scale evolutionary changes within species, natural selection is a process that favors certain traits over others in populations, and phenotype describes the observable characteristics of an organism resulting from the interaction between its genotype and the environment. Thus, uniformitarianism is the only term that