What is the main idea behind uniformitarianism?

The main idea behind uniformitarianism is that the laws of physics and chemistry are consistent over time, which implies that the processes that operated in the past are the same as those observable in the present. This concept is foundational in geology, proposing that by understanding current geological processes, scientists can infer how similar processes shaped the Earth’s surface in the past. This principle allows geologists to study sediment layers, fossil records, and other geological features to piece together the Earth's history.

The concept allows for a gradual understanding of Earth's formation and evolution over long periods, rather than attributing changes exclusively to instantaneous events or catastrophic phenomena. Thus, uniformitarianism emphasizes the continuity of natural laws and processes, which provides a framework for interpreting geological evidence throughout Earth's history.