Uniformitarianism

In its most basic form, uniformitarianism describes a methodology used in studying the Earth’s history. It assumes that the Earth can be interpreted in terms of natural processes that are operational today. In its broader context, uniformitarianism also embraces certain conclusions about Earth's history: that the rates at which these processes operate are constant through time and that the Earth has experienced a cyclic history.

Origin of Uniformitarianism

Uniformitarianism owes its origin and development to three British geologists: James Hutton, who laid the groundwork for the concept; John Playfair, who elucidated and elaborated on Hutton's ideas; and Charles Lyell, who championed the uniformitarian cause in the mid-nineteenth century.

At the end of the eighteenth century, there was fairly close agreement between theories of the Earth based on direct, though limited, observations of Earth material and structure and the account of Earth history revealed in the biblical book of Genesis. The Earth was thought to be of no great antiquity, considered by most to be not much older than six thousand years. The surface features of the Earth, its mountains with their tilted rock, its river valleys, and its ubiquitous surficial gravels, were attributed to a great debacle, assumed to be the biblical flood of Noah. These features existed in equilibrium with the elements, possibly awaiting the next great debacle. Some erosion was happening, but not enough to greatly alter the topography in the short time available. Against this intellectual backdrop, Scottish scientist James Hutton presented to the Royal Society of Edinburgh a paper entitled System of the Earth (1785), which contained the seeds of a controversy that continued for fifty years. The paper was published in the first volume of the Society's Transactions under the title Theory of the Earth: Or, An Investigation of the Composition, Dissolution, and Restoration of the Land Upon the Globe (1788).

Hutton's work outlined the rock cycle. He recognized, as others had before him, that the fossiliferous strata of the continents had formed on the bottom of the sea as unconsolidated sediment. To be added onto the continent, in places at angles of inclination too steep to represent the original repose of water-charged sediment, a mechanism was needed to fuse the sediment into rock and uplift the sea bottom. In Hutton's scheme, the energy required was derived from the Earth's internal heat. Once exposed to the elements, the rocks were eroded to form sediment again. In Hutton's view, the land was derived from a former continent, and the disintegration and erosion of rock observed at its surface provided material for the construction of a future continent. Hutton emphasized that these processes that shaped the Earth were natural and operated very slowly, hardly causing noticeable change during the history of humankind. He eschewed calling upon preternatural causes to explain natural phenomena.

Hutton's 1788 paper contains the significant elements of what was later termed uniformitarianism. The Earth was to be interpreted in terms of present-day natural processes, excluding supernatural explanations. The processes operated very slowly and probably at fairly constant rates, although Hutton was unclear on this latter point. Charles Lyell added a major emphasis on constant rates almost fifty years later. Lastly, the Earth went through a cyclic development, or, as Hutton phrased it, a “succession of worlds,” with the destruction of one world providing material for the next.

Hutton's view of cyclic “worlds” destroyed and reconstructed by slow processes led him to conclude that the Earth is very old, in his phraseology, an earth with “no vestige of a beginning” and, about the cyclicity, “no prospect of an end.” Hutton's “discovery” of an Earth of inscrutable age is considered his major contribution to geology. Hutton is also credited as the first to recognize the true origin of those rocks now known as igneous. His belief that these bodies were injected as molten masses into stratified rock molded his attitude toward the efficacy of heat in driving his cycles.

Neptunism and Plutonism

The prevailing view of these rocks at the time was that of the German mineralogist and natural philosopher Abraham Gottlob Werner, whose science of geognosy maintained that basalt and granite had been chemically precipitated from an ocean that, from time to time, had flooded the Earth. Hutton's adherents became known as Plutonists and Werner's as Neptunists. A few years after the publication of Hutton's 1788 paper, his ideas were acrimoniously attacked by the Neptunists. Although the argument ostensibly was over the origin of basalt, a major undercurrent centered on Hutton's timeless Earth, a story that was not in line with that of the Scriptures. An ailing Hutton attempted to answer these attacks in 1795 with a wordy expansion of his ideas that is notorious for its unreadability. He died in 1797.

notorious for its unreadability. He died in 1797.

Fortunately, Hutton's good friend and sometime field companion John Playfair engaged in the battle with the Neptunists. Playfair's prose was as facile as Hutton's was cumbersome, and it is from Playfair's Illustrations of the Huttonian System of the Earth (1802) that most of posterity's knowledge of Hutton's thoughts come from. In the period following Playfair's elucidation, most geologists came to accept the igneous origin of granite and basalt and to adjust their thinking in line with the unavoidable conclusion that the Earth is certainly much older than the six thousand years afforded it by a literal reading of Genesis.

The most important discovery in the first two decades of the nineteenth century was that the Earth's strata record a progression of life forms with primitive types in lower layers and more advanced types above. Foremost among researchers of the fossil record was the French comparative anatomist Georges Cuvier, who, in 1812, published a monograph that served as a major impetus for renewed controversy surrounding uniformitarianism. Cuvier, one of the first naturalists to reconstruct fossil vertebrates, was recognized as the premier scientist of his day. His early work had been on fossil vertebrates, the mammoth, among many others, found in the surficial gravels. Because he felt that the extinction of this fauna could not be explained by processes presently acting on the surface of the Earth, he concluded that their demise resulted from a sudden but prolonged and localized inundation of the land by the sea brought about by unknown natural causes. He referred to the event as a revolution. Later research in the rocks around Paris caused him to expand his idea of Earth history to include several revolutions.

With his theory of periodic revolutions, Cuvier traditionally has been considered in English-speaking countries as a proponent of an Earth shaped through divinely instituted catastrophes, which, in turn, were followed by special creations to replace the extinguished life. (Martin J. S. Rudwick, in an excellent account entitled The Meaning of Fossils (1972), points out the injustice of this characterization. Cuvier was a strict empiricist who believed that science and religion should be pursued separately.) Cuvier's research was immediately seized by William Buckland, England's most prestigious geologist, who took the latest of the revolutions and transformed it from its original form, a localized inundation of long duration, into a catastrophic, short-lived universal deluge—in short, the flood of Noah. Buckland's flood theory, the so-called diluvial theory, gained much popularity in England in the 1920s but was essentially abandoned toward the end of the decade as it became clear that the surficial gravels, the supposed deposits of the deluge, did not exhibit the distribution or character expected of a worldwide catastrophic event.

Still, a contingent of prominent British Diluvialists believed that the observations on which Cuvier's revolutions were based could not be explained by any of the Earth's operation processes. In response to the threat posed to the uniformity of nature theory by the position of these individuals, who became known as catastrophists, Charles Lyell published his landmark book Principles of Geology (1830-1833), a work built upon the basic tenets of Hutton's theory of the Earth. The ensuing debate between the catastrophists and uniformitarians, as Lyell and his followers became known, was a conflict in viewpoint among scientists, not a struggle between science and the church, as is commonly assumed. In many important respects, the two sides were in agreement. The catastrophists willingly accepted the idea of ancient Earth and were devoted in most situations to the methodology of uniformitarianism. They were firmly opposed, however, to the interpretive aspects that the doctrine imposed on Earth's history: namely, that the slow rates of present-day processes are representative of all time (steady rate) and that Earth's history is cyclic, with one cycle looking much like another (steady state).

On the surface, the catastrophists' argument against steady-rate uniformitarianism seemed to simply request accelerated rates to explain phenomena such as those on which Cuvier's revolutions were based. It is clear from their writings that the catastrophists were anxious to interpret these episodes as times during which natural law was suspended by the regulatory hand of God. Their view of God was that of both creator and referee, willing to intervene in his creation if it veered off track. To them, any movement to remove the punitive hand of God from the course of things would lead to moral decay and the disintegration of British society. Lyell, in contrast, was unwilling to concede any portion of the Earth’s history, no matter how small, to a supernatural cause that fell outside the pale of scientific inquiry. As succinctly analyzed by Charles Coulston Gillispie in his revealing account of the times entitled Genesis and Geology (1951), the catastrophists were apprehensive that without any cataclysms, there would be no God. In contrast, Lyell was concerned that without the uniformity of nature, there would be no science. Lyell's opinion eventually prevailed, and supernatural explanations, for at least the physical world, were expunged from the methodology of historical interpretation. As a companion to this development, the efficacy of gradual processes in explaining all historical phenomena became firmly established in geologic dogma, but not without some unfortunate side effects.

To the catastrophists, Lyell's stubborn support of steady-state uniformitarianism not only seemed palpably false in the light of a fossil record that showed progression but also was contrary to physical laws that required the Earth to evolve as its energy dissipated. In light of twenty-first century knowledge, Lyell's arguments against the evidence of the fossil record seem foolish. He went so far as to predict that ichthyosaurs—marine reptiles seemingly extinct for more than 65 million years—would return to populate the seas when their “world” once again rolled around. In his short, provocative book Time's Arrow, Time's Cycle (1987), Stephen Jay Gould, argues that differing views of history occupied a central position in the conflict between the two sides. Lyell's repetitious Earth (time's cycle) was essentially ahistorical because it developed no unique configurations through time. Opposed to this was the catastrophists' vision of an ever-changing Earth (time's arrow), unique at each stage and thus amenable to sophisticated historical analysis. Lyell abandoned his stand on steady-state uniformitarianism shortly after Charles Darwin's convincing documentation that life on Earth had evolved.

In the twenty-first century, uniformitarianism remains a foundational theory used for studying the Earth’s history. Although it has evolved, its general understanding of Earth’s past leads to an understanding of its present remains. Modern uniformitarianism, however, acknowledges that gradual processes and large-scale cataclysmic events were responsible for shaping the Earth. Uniformitarianism also evolved to include many sciences that were not known when the theory was first posited. 

Principal Terms

catastrophists: adherents to the belief that the present-day slow rates of natural processes are not sufficient to explain many features of the rock record

diluvial theory: the belief that the Mosaic flood was responsible for shaping many of the Earth's surface features

doctrine of final causes: the belief that a purpose or design is revealed in the organization of nature

methodological uniformitarianism: that aspect of uniformitarianism that describes a procedural approach to the study of the Earth—that is, that ancient phenomena can be interpreted in terms of present-day natural processes

Neptunists: adherents to Abraham Werner's belief that granite and basalt formed by chemical precipitation from seawater

Plutonists: adherents to James Hutton's belief that granite and basalt formed by crystallization from molten mineral matter

rock cycle: the path of Earth materials as erosional products of rock are deposited and reformed again into rock, which then can be eroded again

substantive uniformitarianism: that aspect of uniformitarianism that draws conclusions about the history of the Earth—that is, that natural processes have been taking place at constant rates through time and that the Earth has had a cyclic history

surficial gravels: alluvium found at different places on the Earth's surface, originally interpreted as the product of the Mosaic flood

uniformity of nature: Charles Lyell's formulation describing a nature in which processes are both consistent and constant through space and time; a mixture of methodological and substantive uniformitarianism

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