by Greg Mayer

Our fourth installment of Teaching Evolution is an extract from Principles of Geology, by Charles Lyell. Lyell was an enormously influential scientist, and a leading figure in scientific circles in 19th century Britain. His influence on Darwin was profound: in Janet Browne’s authoritative biography of Darwin, the entry for Lyell in the index of volume one goes on for 28 lines, and for 27 lines in the second volume!

In the first half of the 19th century, the links between biology and geology were much closer that they are now. Both were branches of natural history, and Darwin first made his name as a geologist, before his more biological contributions came to dominate his reputation. Lyell’s Principles were required reading for anyone involved in discussions of organic evolution. The current divorce between the academic disciplines is regrettable.

When I was helping plan a major in ecology, evolution, and conservation a few years ago, a survey of a broad range of the best undergraduate majors across the United States showed that none required any geology (though many required years of chemistry and/or physics). A notable innovation of our new major was that it required foundational work in geology for students in the biological sciences. (The major, unfortunately, was nixed by our dean before it got implemented.)

Charles Lyell (1797-1875) is perhaps the greatest geologist of all time. As the American paleontologist David Raup once remarked, “Lyell is to geology what Darwin is to biology.” Lyell’s signal achievement was to turn geologists to the study of observable physical, chemical, and biological processes, and to make these processes the first choice when seeking explanations for the events of Earth history. His method may be epitomized by the phrase “the present is the key to the past”. Born in Scotland and trained as a lawyer, for most of his life he supported himself and his family by the sales of his books. A close friend of Darwin’s, he helped arrange the first publication of Darwin’s views on natural selection, alongside Wallace’s independent discovery of the same principle. Despite this, Lyell did not accept evolution until several years after the publication of the Origin. Lyell’s masterwork, Principles of Geology (1st ed. 1830-1833), which went through 11 editions in his lifetime, was informed by his wide field experience in Europe and North America. He is buried, like Darwin, in Westminster Abbey.

Reading:
Lyell, C. 1830-1833. Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation. Three volumes. John Murray, London. Vol. 3, Chaps. I, IV.

Study Questions:
1. What does Lyell identify as the chief impediment to the first geologists achieving a sound theory of the Earth’s history?

2. What types of studies have led to progress in geology?

3. How may the relative ages of rocks be determined? What sort of evidence does Lyell consider the most useful in this regard?

4. What does Lyell mean by a “zoological province”? How does he use this concept to help establish chronology?

[The other installments of Teaching Evolution can be found by clicking ‘MOOC’, under “filed under” or “tags”, just below.]