The Ecology Book

23

U

niformitarianism is the

theory that geological

processes, such as the

laying down of sediment, erosion,

and volcanic activity, occur at the

same rate now as they did in the

past. The idea emerged in the late

18th century, as mining, quarrying,

and increased travel brought ever

more geological features to light,

including unusual rock strata and

previously unknown fossils, whose

origins were then widely debated.

The generally accepted view

that Earth was only a few thousand

years old had been challenged by

the Comte de Buffon, and in 1785

Scottish geologist James Hutton

also argued for Earth’s far greater

antiquity. Hutton’s ideas were

formed during expeditions around

Scotland to examine layers of rock.

He believed that Earth’s crust was

constantly changing, albeit mostly

slowly, and could see no reason to

suggest that the complex geological

actions of layering, erosion, and

uplifting took place faster in the

distant past than they did in the

present. Hutton also understood

that most geological processes

happen so gradually that the

features he was discovering must

be astronomically old.

Uniformitarianism was not

generally accepted at once, not

least because it challenged a literal

interpretation of the creation stories

of the Old Testament. However, a

new generation of geologists, such

as John Playfair and Charles Lyell,

threw their intellectual weight

behind Hutton’s ideas, which also

inspired a young Charles Darwin. ■

THE STORY OF EVOLUTION

NO VESTIGE OF A

BEGINNING, NO

PROSPECT OF AN END

UNIFORMITARIANISM

IN CONTEXT

KEY FIGURE

James Hutton (1726–97)

BEFORE

1778 The Comte de Buffon, a

French naturalist, suggests

that Earth is at least 75,000

years old—far older than most

people believed at the time.

1787 German geologist

Abraham Werner proposes

that Earth’s layers of rock

formed from a great ocean that

once covered the entire planet.

His followers became known

as Neptunists.

AFTER

1802 James Hutton’s theory

of uniformitarianism reaches a

wider audience when Scottish

geologist John Playfair

publishes Illustrations of the

Huttonian Theory of the Earth.

1830–33 Principles of Geology,

by Scottish geologist Charles

Lyell, supports and builds on

the uniformitarian ideas of

James Hutton.

... from what has actually

been, we have data for

concluding [what] is

to happen thereafter.

James Hutton

See also: Early theories of evolution 20–21 ■ Evolution by natural selection 24–31

■ Moving continents and evolution 212–213 ■ Mass extinctions 218–223

US_022-023_Extinction_and_Change_Uniformitarianism.indd 23 22/11/2018 17:50