Charles Lyell: Principles of Geology
[adapted from
http://www.pbs.org/wgbh/evolution/library/02/4/l_024_01.html]
It's been called the most important scientific book ever. A stunning claim, but
certainly Charles Lyell's Principles of Geology, published in 1830, shook
prevailing views of how Earth had been formed. His book was an attack on
the common belief among geologists and other Christians that unique
catastrophes or supernatural events -- such as Noah's flood -- shaped Earth's
surface. According to this view, a once-tumultuous period of change had
slowed to today's calmer, more leisurely pace. Lyell argued that the
formation of Earth's crust took place through countless small changes
occurring over vast periods of time, all according to known natural laws. His
"uniformitarian" proposal was that the forces molding the planet today have
operated continuously throughout its history. He also wrongly assumed that
these causes must have acted only with the same intensities now observed,
which would rule out asteroid impacts and the like.
Darwin read Lyell's landmark text while on the Beagle, and was much
inspired by it. His own experiences during the voyage backed up the
geologist's theories about how the shifting crust of the Earth was one of
these long-acting, gradual, planet-sculpting forces. While in Valdivia, Chile,
Darwin experienced a two-minute earthquake that terrified him and caused
damage up the coast in Concepcion. Reports from outlying areas revealed
that volcanoes had been active, and Darwin and the Beagle's captain, Robert
Fitzroy, measured an eight-foot uplift of the land. Darwin reckoned that
volcanoes were connected by magma underground, and that pressure not
released through eruptions could cause earthquakes. Thus these different
phenomena were different aspects of the forces Lyell believed had operated
over geological time to produce the world we see now.
"The present is the key to the past," was the motto of uniformitarian science.
And Darwin, greatly influenced by Lyell, extended that principle to biology.
Species, like geologic features, evolved gradually or died out gradually. Like
the forces Lyell talked of, the shifting and rising and falling of land, Darwin
held that the forces seen today in the biologic world -- reproduction,
inheritance, and competition -- gradually produced the whole diversity of life
on Earth. There, Lyell could not, and did not, go. He believed that every
animal or plant, including humankind, was adapted to the niche in which it
was created.