Earth, Our Environment - Class Notes
Charles Lyell and Uniformitarianism

Hutton published a book outlining his concept of "Geology" but was not very skilled in written explanations. His work was later clarified in a book by Playfair and then restructured in the classic "Principles of Geology" by Charles Lyell (1797 - 1875).

Lyell's views differed somewhat from Hutton's. He was the first to expound the idea we know today as Uniformitarianism, often summarized in the statement "the present is the key to the past".

We interpret "the present is the key to the past" to mean that the same processes and laws in operation today were operating throughout the history of Earth. Lyell interpreted the idea more strictly, he also assumed that processes operated at the same rates in the past as they do today. He rejected the idea that Earth history was dominated by catastrophic events, he favored gradualism.

We now know that Earth history, although dominated by gradual processes, was punctuated with catastrophic events such as mass extinction's (perhaps caused by comet impacts, periods of dramatic climate change or intense volcanism). For dramatic example, in July of 1994 the comet Shoemaker-Levy 9 crashed into Jupiter! But such events are a natural process that are expected.


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Prepared by: Charles J. Ammon
January 1997