Uniformitarianism is among the primary doctrines in the science of geology. It states that all processes that can be seen sculpting the Earth today have operated throughout geologic time and will continue to operate in the future. This also lends itself to the idea of “gradualism,” whereby change in our world is slow and gradual because that is what we observe on Earth today. We see lakes and streams that slowly deposit centimeters of silt and mud per year, and the casual erosion by the Colorado River that has carved so deeply into the sandstones of Arizona created a scar that lays bare billions of years of depositional history. Using the principle of uniformitarianism, geologists can gain great insights into the formation of very old rock. By comparative analysis of the patterns and internal structures of old rocks and the structures of newly forming rocks in particular environments, geologists can safely infer which types of rock form in different environments.
The shifting dunes that populate the deserts in the more arid regions of the globe are products of wind blown sand. When analyzed, the rock particles that are incorporated in the microstructure of the dune have a characteristic form and dimension. When rocks of a similar structure are located beneath a modern temperate forest, geologists can deduce that when those rocks were deposited, the environment in which they were deposited was very dry, hot, and vastly different from the present ambience. The principle of uniformitarianism suggests that because the rock that is currently forming in the dune shares a very distinctive structure with older previously formed rocks, the two rocks are related because they seemed to have formed in the exact same manner. This illustrates a common occurrence in modern geology: a current overlaid environment floored by rock layers that were deposited in radically different climates. In most situations these observations can be explained using the principle of uniformitarianism. For hundreds of years geologists have concluded that the principal holds true, and it continues to be a useful reasoning tool when deciphering geological puzzles.
Originally dubbed the Huttonian theory by James Hutton (1727-1797), and occasionally referred to as “actualism,” uniformitarianism is a cornerstone of geology and contributes to many other sciences. In many branches of science, initial logical assumptions must be agreed upon and understood before anything novel can be gleaned from research. Uniformitarianism is one of geology’s essential assumptions. Hutton, a Scottish farmer and physician, is considered to be the founder of modern geologic thought and was the first to recognize and describe the cyclic processes of the Earth. At his home in Scotland, Hutton was impressed by the sedimentary layers of sandstone that were once laid down horizontally (formally called the “Law of original horizontality”), but were now thrust up vertically and capped with younger layers perpendicular to the vertical beds. He realized that the cycle of uplift, erosion, deposition, solidification into rock, and finally uplift again was visible in the Earth’s layers and the whole of the cycle could be deduced from looking at present rock strata (individual rock layers that represent specific depositional events). In 1795 he published his two-volume work entitled Theory of the Earth, with Proofs and Illustrations, which contained the first real counter-theory to the previous dogma of Catastrophism. There is, he wrote “no vestige of a beginning, no prospect of an end” to the geologic cycles of Earth. Hutton’s visionary and controversial insights into geologic processes and the rock record allowed many later geologists to accredit him for being the first to conceive of the principal of uniformitarianism, which laid the groundwork for future scientists to make a profound discovery that changed the face of geology permanently: the earth is extremely old. However, this concept drastically altered the current perception of biblical occurrences guiding geology, which, up until then, were considered responsible for all land features. Uniformitarianism’s paradigm altering agenda wasn’t clearly an accepted doctrine until the 19th century. Expanding on Hutton’s principals, a fellow Scotsman, John Playfair, in his Illustrations of the Huttonian Theory (1802), made little headway competing against the upheld religious dogma. For religious scholars, the suggestion that geological history reached much further back than what was allowed for in the Bible was absurd. It is clear that the process of erosion is painstakingly slow and, if the principle of uniformitarianism holds, the enormous amount of time needed for rock to be uplifted, eroded, formed into rock again, and be lifted up forming mountains is nearly incomprehensible. Since its initial rationalization, the principal of uniformitarianism has been fought at every turn; however, it remains today as a guide for all geologic explanations and reasoning.
After Hutton’s initial description of the principle, Charles Lyell (1797-1875) formulated it into the doctrine as it is known today. Lyell, a British lawyer and honored geologist, was, perhaps, the greatest advocate of uniformitarianism. His work in the then-budding field of geology propelled this principle to become a mainstay of geologic reasoning, dislodging the preeminent theory of the day: Catastrophism. His magnum opus, Principles of Geology, in which his gradualist, uniformitarianist views on geology were ostentatiously exhibited, was accepted and used as a sounding board for many new scientists such as Charles Darwin and Alfred Russel Wallace. At the time, however, many of Lyell’s contemporaries, such as the polymathic William Whewell, disliked the idea of a uniform and consistent world. Whewell’s defense of catastrophism in light of uniformitarianism was grounded in a more empirical stance from such evidence as the fossil record. Even the earliest studies of the fossil record reveled gaps in the types and numbers of species that lived at different layers of strata. This insight was not perfectly in line with Lyell’s work and as a result of Whewell’s counterarguments, Lyell was forced to constantly defend and clarify his theory. Through his struggle, Lyell’s work decidedly erected the scaffold from which modern geology was constructed. From this, many future scientists built upon this principle, and combined its logic with their own sciences’ philosophy to form other hypothesizes that established many new and creative approaches to scientific quandaries.
The English anthropologist Sir Edward Burnett Tylor (1832-1917) also utilized the principle of uniformitarianism in expressing his hypothesis that civilized society had evolved through nonsupernatural processes from “savage” societies similar to those encountered throughout many parts of the globe. In his book, Primitive Religion, he explores the notion that human cultures, and especially religions, are products of natural, regular, progressive and uninterrupted expansion of the mental capacities of Homo sapiens. This apparent progression could be seen as a reflection of uniformitarianism and Tylor used this comparison to further his notion as a reasonable and sound science.
Although the principals of uniformitarianism and catastrophism have been at odds for centuries, with many champions on both sides that fought for a spectrum of reasons, the principle of uniformitarianism survives and is still taught today in modern geology classes around the world. Usually the tendency is to teach a synthesis of the two principals because it is clear now that both have had an enormous impact on, not only the appearance of the Earth’s surface, but also on the very inhabitants that occupy it.
- Albritton, C. C., Jr. (Ed.) (1975). Philosophy of Geohistory, 1785-1970: Benchmark papers in geology, Vol. 13. New York: John Wiley.
- Gould, S. J. (1987). Time’s arrow time’s cycle. Cambridge, MA: President and Fellows of Harvard College.
- Palmer, T. (1999). Controversy catastrophism and evolution: The ongoing debate. New York: Kluwer Academic/Plenum Publishers.