Which scientist introduced the theory of uniformitarianism?

The theory of uniformitarianism, which posits that the Earth has been shaped by the same natural processes still in operation today over vast periods of time, was significantly advanced by Charles Lyell. In his work "Principles of Geology," Lyell argued that we can understand Earth's history and geological formations by studying current geological processes, like erosion and sedimentation, rather than resorting to catastrophic events.

This concept was crucial in changing the way scientists understood geological time and processes, allowing for a more gradual understanding of Earth's history rather than one dominated by sudden, large-scale changes. While James Hutton also contributed to the foundation of this theory, it was Lyell who effectively popularized and formulated it in a way that influenced future geological thought. Hence, Lyell is often credited with formally introducing and solidifying uniformitarianism as an essential principle in geology.