Final answer:
Charles Lyell's geologic theory of uniformitarianism, suggesting a much older Earth shaped by gradual processes, supported Darwin's evolutionary theory by providing a time frame in which natural selection could produce diverse species.
Step-by-step explanation:
Charles Lyell's Influence on Darwin's Theory
Charles Lyell, a prominent 19th-century geologist, developed a geologic theory known as uniformitarianism. His work described how Earth's landscapes are shaped by gradual processes, such as erosion and sedimentation, rather than solely by catastrophic events. In his influential text, Principles of Geology, Lyell argued that the Earth had to be significantly older than the 6,000 years as was commonly believed at the time. This implied that there was enough time for evolution to occur.
Lyell’s ideas provided an important framework for Charles Darwin. Darwin observed geological formations during his voyage on the HMS Beagle and noted evidence such as fossils of sea creatures in high mountains, which reinforced Lyell's notion of a constantly changing Earth. Understanding that Earth had a deep geological time scale allowed Darwin to conceive of natural selection as a process that occurs over eons, gradually shaping life on Earth.