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Uniformitarianism: Definition, Principles & Examples

Lesson Transcript
Instructor: Charles Spencer

Charles teaches college courses in geology and environmental science, and holds a Ph.D. in Interdisciplinary Studies (geology and physics).

Uniformitarianism is an important concept in geology that addresses the consistent behavior of geological processes over time. Learn about the concept and significance of uniformitarianism in this lesson, and then test your knowledge with a quiz.

Definition of Uniformitarianism

Uniformitarianism is the name given to the idea that natural processes behave more or less in the same way today as they have throughout the past, and will continue to do so in the future. Although it can apply in any science, it was a cornerstone for the development of the science of geology.

The term was first used by William Whewell in the forward he wrote to Principles of Geology: the first textbook about the study of the earth, written in 1830 by Charles Lyell. But the concept dated to the late 1790s writings of James Hutton.

Hutton, a Scottish minister and naturalist, wrote about the relationships he saw between two beds of sandstone exposed at Siccar Point in Scotland. There, he observed horizontal beds of sandstone resting atop layers of sandstone tilted nearly vertically. In the prevailing view of the day, called catastrophism (a term also coined by Whewell in his forward), these beds had been deposited in a large, short-lived event.

Hutton didn't see it that way. He saw a cycle of deposition, erosion, and deposition that had occurred over a significant amount of time, and concluded that the older bed (the one on the bottom) had been deposited horizontally, then tilted and eroded prior to deposition of the younger one.

What was insightful about his thinking was that he based this interpretation on his observations of how modern rivers eroded and deposited sand along the coast of Scotland. He also realized that the sandstone beds had been formed from sand deposited in exactly the same way (in other words, slowly).

Significance of Uniformitarianism

Uniformitarianism (which also came to be known by the term gradualism) competed for acceptance with catastrophism and eventually displaced it. But you might be asking yourself: Why was it such a big deal?

The answer is that Hutton was the first person to recognize (at least in published work) that we could understand much about how geologic features (such as valleys, sedimentary rocks, and mountains) came to be by observing the events of the present day. Uniformitarianism gave us a tool to interpret the geologic past. In fact, geologists sometimes summarize the concept in the phrase: The present is the key to the past.

The concept is applied to all types of geologic processes. For example, rivers erode valleys and build deltas gradually. Mountains rise at an imperceptible rate and erode just as slowly. Stalactites require uncounted years to form (as do the caves in which they are found). Rocks weather bit by bit, and the resulting sediment is deposited incrementally, layer upon layer, to eventually become sedimentary rocks.

The other big idea inherent in uniformitarianism is that Earth is a very old place. For slowly operating processes (like river deposition) to create geologic features (like a delta) required a much more ancient age for Earth than catastrophism assumed. So, the idea of the immensity of geologic time (sometimes called deep time) also began with Hutton's work.

Modern View of Uniformitarianism

Modern geologists interpret the idea in a slightly different way than it was originally conceived, but it is still an indispensable concept in interpreting the geologic history of our planet.

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