Which geologist's 'Principles of Geology' greatly influenced Darwin?

Charles Lyell’s Principles of Geology greatly influenced Charles Darwin. Lyell argued that the same gradual natural forces visible today—such as erosion, volcanic activity, and uplift—had shaped Earth over immense spans of time.

The book was published in multiple volumes between 1830 and 1833. Robert FitzRoy gave Darwin the first volume shortly before HMS Beagle’s second voyage began in 1831. Darwin used Lyell’s ideas to interpret landscapes and rock formations during the expedition.

A common mix-up is James Hutton, whose earlier work helped establish the foundations of uniformitarian geology. Lyell did not invent every underlying idea, but he developed and popularized them in a systematic, widely read form. Lyell opposed Darwin’s evolutionary conclusions for much of his life, yet his emphasis on deep time was crucial to Darwin’s thinking.