What methods did Charles Lyell use in Principles of Geology to explain Earth's history?

In his seminal work Principles of Geology, Charles Lyell championed the doctrine of uniformitarianism to explain Earth's history, rejecting the then-prevailing school of catastrophism.12

Lyell’s methodology was grounded in two primary propositions:
* Consistency of Causes: He argued that the geologic processes currently shaping the Earth—such as weathering and sedimentation—are the same forces that have operated throughout history.12
* Uniform Intensity: He maintained that these processes have always operated at the same average levels of energy, effectively viewing Earth as a steady-state system.1

By applying these Huttonian principles, Lyell provided a framework for inferring past geologic events directly from the evidence found in rocks. His approach emphasized that the present is the key to the past, allowing scientists to account for all geologic change through natural physical, chemical, and biological processes rather than supernatural intervention. This rigorous focus on methodology and the rejection of preternatural causes established a foundation for modern geology and influenced the development of evolutionary biology.123