Charles Lyell was a British geologist noted for establishing the principles of uniformitarianism, the idea that features of the Earth's surface were produced by natural forces operating for long times (1830s). Prior to Lyell, most scientists were catastrophists, meaning they believed that changes in geological features were due to rapid forces, namely natural catastrophes. This belief was in close accordance with accounts of the Earth's history recorded in the Bible, meaning the Bible and science were still treated as harmonious. However, Lyell was, along with the earlier John Playfair, the major advocate of James Hutton's idea of uniformitarianism, that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. Uniformitarianism was embraced by those who also supported the theory of evolution because evolutionary processes also occurred over very long time scales. Lyell supported Charles Darwin's theories of evolution.

Principles of Geology, Lyell's first book, was also his most famous, most influential, and most important. First published in three volumes in 1830-33, it established Lyell's credentials as an important geological theorist and propounded the doctrine of uniformitarianism. It was a work of synthesis, backed by his own personal observations on his travels. The central argument in Principles was that the present is the key to the past. Geological remains from the distant past can, and should, be explained by reference to geological processes now in operation and thus directly observable. Lyell's interpretation of geologic change as the steady accumulation of minute changes over enormously long spans of time was a powerful influence on the young Charles Darwin. Lyell asked Robert FitzRoy, captain of HMS Beagle, to search for erratic boulders on the survey voyage of the Beagle, and just before it set out FitzRoy gave Darwin Volume 1 of the first edition of Lyell's Principles. When the Beagle made its first stop ashore at St Jago, Darwin found rock formations which seen "through Lyell's eyes" gave him a revolutionary insight into the geological history of the island, an insight he applied throughout his travels.

Lyell's most important specific work was in the field of stratigraphy. From May 1828, until February 1829, he traveled with Roderick Impey Murchison to the south of France and to Italy. In these areas he concluded that the recent strata (rock layers) could be categorized according to the number and proportion of marine shells encased within. Based on this he proposed dividing the Tertiary period into three parts, which he named the Pliocene, Miocene, and Eocene.

Sources

• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2008. "Lyell, Charles." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth September 15, 2006; Last revised December 1, 2008; Retrieved June 24, 2009]. 
• Wikipedia Contributors, Charles Lyell, Wikipedia The Free Encyclopedia, Accessed 24 June 2009.