Charles Lyell, a British lawyer turned geologist, was the first prominent Western thinker to establish that small geologic processes (like rainfall) accomplish big things (such as washing away a mountain).

Lyell became a lawyer in 1820 but switched over to geology full-time in 1827. He began publishing papers, helping to make geologic maps, and in 1830 published the first volume of the multi-volume Principles of Geology.

It was not his only work, but it changed the way people viewed the Earth and laid the foundation for modern geology.

Catastrophism

Lyell came after William Smith and other early 19th-century geologists had connected British and European rock formations and fossils into a mappable history of the Earth.

They saw the world’s history as a series of great changes recorded in stone: mountains suddenly soaring; volcanoes forming in a cataclysm; groups of living organisms going extinct and being replaced by a new group.
 

This catastrophic view was the one taught at Oxford, where Lyell studied under William Buckland. It didn’t sound right to Lyell.

The present is the key to the past

The softest things of the world
Override the hardest things of the world

— Tao Te Ching, Chapter 43

A devout Christian Charles Lyell wouldn’t have cared for Lao-Tze’s philosophy, if he ever encountered it. It took him several revisions of Principles to come to terms with the theory of evolution!

His faith didn’t conflict with his controversial view of gradual change over Earth’s history, though. He rejected catastrophism completely.

Never was there a doctrine more calculated to foster indolence, and to blunt the keen edge of curiosity, than this assumption of the discordance between the former and the existing causes of change… The student was taught to despond from the first. Geology, it was affirmed, could never arise to the rank of an exact science… [With catastrophism] we see the ancient spirit of speculation revived, and a desire manifestly shown to cut, rather than patiently untie, the Gordian Knot.- Sir Charles Lyell, “Principles of Geology,” 1854 edition; quoted by Stephen Jay Gould and in Wikipedia.

Some had already attempted to treat the knot gently. James Hutton, an 18th century geologist and prominent figure during the Scottish Enlightenment, had suggested that Earth’s past could be explained in terms of the geologic processes going on today.

Charles Lyell worked that out in great detail.
 

Geologic time

The gradualism proposed by Hutton and Lyell called for a lot of time.

If Earth has a fairly short history, as extrapolated from the Bible, then catastrophic change, like a flood, is needed to explain the existence of, say, a valley.

However, today’s processes can accomplish the same effect, given enough time. Gradual erosion from rain, wind and flowing water can form a valley and do much, much more over many millions of years.
 

Charles Lyell was aware of stratigraphy and would make many contributions to the field, but in Principles he emphasized process, that is, gradualism (sometimes called uniformitarianism), over time.

The full title of his book, after all, was Principles of Geology, Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation.

Author Joe Burchfield says:

Time, indefinite drafts of time, was necessary for Lyell’s gradualism, but in its fervent antidirectionalism [the idea that Earth was not shaped by God for a purpose], his notion of the Earth’s dynamics was curiously atemporal.

Principles did establish the basis for the modern science geology. It underwent 12 revisions over Lyell’s lifetime as its author’s ideas evolved and as he added more information.

A measure of the lasting impact of Lyell’s theory of gradualism is the strong resistance encountered by 20th-century proponents of catastrophic causes for individual events – the K-T extinction, for example, or the great Missoula floods that carved the landscape of parts of the northwestern US.

Today we recognize that geologic change can happen slowly or very, very quickly. The various, well-publicized clashes aside, many of us also do maintain, as Sir Charles Lyell did, a sense of faith and mysterious purpose in life – this is appropriate, in a world we did not create and which both nourishes us and holds the power to destroy us in an instant.

Charles Lyell is one of the

Sources:

The History of Evolutionary Thought. Uniformitarianism: Charles Lyell. University of California at Berkeley.

The age of the Earth and the invention of geological time. Joe D. Burchfield. (PDF)