Uniformitarianism is a geological principle that suggests the processes shaping the Earth today are the same as those that occurred in the past. This concept implies that natural laws and processes, such as erosion, sedimentation, and volcanic activity, have remained consistent over time. It helps scientists understand Earth's history by studying current geological processes. The idea of uniformitarianism was popularized by the geologist Charles Lyell in the 19th century. It contrasts with catastrophism, which emphasizes sudden, dramatic events like meteorite impacts or volcanic eruptions as primary forces of change. Together, these concepts help explain the Earth's geological features and history.