Charles Lyell (1797-1875)

    Following up on the work of James Hutton, Lyell was the principal proponent of the geological theory of Uniformitarianism, which proposed that the Earth's geological features could be understood in terms of observable, gradual processes (such as floods, glaciers, volcanoes, & earthquakes) operating over vast periods of times (millions of years). This replaced the previously accepted theory of Catastrophism, in which geological features were understood as consequences of rapid, catastrophic events (principally Noah's Flood) operating over a very short history (the few thousand years since the Creation). Lyell's book, "Principles of Geology", first published in 1830, was a strong influence on the young Charles Darwin.

Gradual processes include vulcanism (Mt Vesuvius caldera, Italy [left]) and glacial scouring (Zermat Glacier, Switzerland [right]).