Uniformitarianism: Charles Lyell (1 of 3)

Discrete rock layers containing different fossils reinforced the idea that the Earth’s history could be divided into ages marked by catastrophic change. However, gradual change, like that caused by erosion, has also played an important role in the Earth’s history.

Thanks to the pioneering work of researchers such as William Smith, geologists in the early 1800s were able to swiftly organize rock formations into a single colossal record of Earth’s history. Many geologists saw in this record a stormy epic, one in which our planet had been convulsed repeatedly by abrupt changes. Mountains were built in catastrophic instants, and in the process whole groups of animals became extinct and were replaced by new species. Giant tropical plants, for example, left their fossils in northern Europe during the Carboniferous Period, never to be seen there again. Earth’s history might not fit a strict Biblical narrative any longer, but these revolutions seemed to be a sign that it did have a direction. From its formation, catastrophes altered the planet’s surface step by step leading towards the present Earth. Life, likewise, had its own arrow through time.

Catastrophism
Even before this geological evidence had emerged, some naturalists had already claimed that Earth’s history had a direction. Buffon, and later the physicist Joseph Fourier (1768-1830), both claimed that the Earth had begun as a hot ball of molten rock and had been cooling through time. Fourier argued that the tropical plants of Europe must have lived during those warmer times. Some geologists suggested that the cooling of the planet occasionally triggered violent, sudden uplifts of mountains and volcanic eruptions.

• Rock layers image courtesy of David Smith, UCMP.
• Lyell image courtesy of Dennis O’Neil, Palomar College.