Final answer:
The theories of geological evolution are based on the principles of uniformitarianism and gradualism, provided by Charles Lyell and James Hutton, which posit that slow geological processes have always been at work, implying an older Earth and supporting Charles Darwin's theory of evolution.
Step-by-step explanation:
The theories of geological evolution and the principles used to support them include the contributions of several key figures, prominent among them being Scottish geologist Charles Lyell, who posited uniformitarianism.
Uniformitarianism suggests that geological processes operating in the present have been constant over time. This idea was critical in extending the perceived age of the Earth and provided a foundation for Charles Darwin's theory of evolution. Lyell's views supported the gradual mechanisms of evolutionary change proposed by Darwin, allowing for a more credible theory that encompassed both biological and geological observations.
The concept of uniformitarianism was in contrast to the then-dominant belief in catastrophism, which posited Earth's features were the result of quick, massive events. The slow, consistent processes proposed by Lyell, as well as earlier by James Hutton, implied a much older Earth, providing more time for the gradual evolution of species. These principles are fundamental to the science of geology and are integral to our understanding of Earth's history.
The ideas of James Hutton and Charles Lyell significantly influenced Charles Darwin's work. Hutton's and Lyell's understanding of geological change through gradual, continuous processes, opposed to sudden, substantial changes, provided an analogy for Darwin's support of gradualism in evolutionary change. This lent credence to Darwin's hypothesis of natural selection, as the extended time scale allowed for the subtle changes necessary for species to evolve.