Charles Lyell is remembered for popularizing uniformitarianism theory. This theory grew out of the earlier work of James Hutton and held that Earth's geological history could best be explained as a long series of gradual changes. This notion stood in stark contrast to the then-current doctrine of catastrophism, which contended that Earth's landforms had been shaped by a limited number of catastrophic events in historic times.
In 1830, Charles Lyell published "Principles of Geology," which laid out the principle that the past is key to the present and depicted the gradual forces that have shaped the Earth throughout recorded history as having operated over a far longer timescale. Charles Darwin read the book immediately after its publication during his historic voyage aboard the Beagle and was heavily influenced by the author's theory.
Uniformitarianism overturned earlier ideas about the way the Earth was formed by arguing that extraordinary events, such as a global flood, were superfluous. Lyell's adaptation of Hutton's work made the case that a set of slow, uniform processes had operated across the world over a period of time far greater than 19th-century science had anticipated. Uniformitarianism has since been modified to allow for sudden, dramatic events such as asteroid impacts, but the key idea about ancient geology operating in the same way as present geology is central to Earth sciences and biology.