Catastrophism

Historically, catastrophism was the doctrine that a series of sudden and violent events caused widespread or even global effects, producing the differences in fossil forms and other features found in successive geological strata. More recently, a new school of catastrophism has arisen, prompted by growing evidence that much of the geological record, including mass extinections of living organisms, has been greatly influenced by rare events of large magnitude, such as widespread flooding, volcanic activity, and asteroid impacts.

Neptunism and Vulcanism

Although the term catastrophism is usually associated with the work of Georges Cuvier near the beginning of the nineteenth century, most theories of Earth's history before that time involved various ideas of catastrophism, emphasizing sudden and violent events rather than gradual processes. Based on the biblical account of creation in six days and genealogies of the descendants of Adam, most writers assumed that the Earth was only about six thousand years old. Early theories of the Earth's surface features were based on the biblical account of Noah's flood. In early eighteenth-century England, Thomas Burnet and John Woodward used the idea of a universal flood to explain geological phenomena such as the formation of mountains and valleys, irregularities in strata, and the existence and location of fossils. These ideas stimulated the collection of fossils as evidence of biblical veracity.

In Italy, where volcanoes were active, Venetian priest Anton Moro suggested in 1740 that Noah's flood was a more localized event and that rock strata formed from a series of violent volcanic eruptions that entombed plants and animals, forming fossils in the rocks. These catastrophic ideas were sometimes viewed as complementary; by the late eighteenth century, however, they led to a controversy between the Neptunists, who stressed the role of water and floods, and the Vulcanists, who emphasized fire and heat.

In 1749, Georges Leclerc, Comte de Buffon, keeper of the King's Gardens in Paris, suggested a speculative natural history of the Earth with a vastly expanded time scale. Instead of a recent six-day creation, he proposed seven epochs of development over about 75,000 years. Using calculations devised by Sir Isaac Newton for estimating the cooling of comets, Buffon experimented with the cooling of a red-hot globe of iron; he extrapolated his findings for a mass the size of the Earth, arriving at an estimate that it would have taken 74,832 years for the Earth to cool to its present temperature. By the time he finished his Épochs de la Nature (1779), Buffon had divided his history of nature into seven “epochs” as metaphors of the seven “days” of creation.

Although his treatise did not refer to catastrophism, Buffon's epochs included catastrophic events of fire and water. In the first epoch, the Earth formed out of matter ejected from a collision of a comet with the sun. As the Earth solidified in the second epoch, its crust wrinkled to form the mountain ranges. In the third epoch, vapors condensed as the Earth cooled, covering the Earth with a flood in which fish flourished and sediments formed, enclosing fossils and organic deposits such as coal. The fourth epoch began after further cooling produced subterranean openings, causing a rush of waters, earthquakes, and volcanoes that produced dry lands. Land animals and plants appeared in the fifth epoch, and the continents moved apart in the sixth after migrations of animals had separated various species. Finally, wrote Buffon, humans appeared in the seventh epoch.

By the end of the eighteenth century, the Neptunists and Vulcanists became more sharply divided. The British geologist Sir William Hamilton developed in more detail the implications of Vulcanism from the action of volcanoes. He identified basalt and other rocks found near volcanoes as products of lava flows. He argued that volcanic action played a constructive role in uplifting new land from the sea, shaping the landscape, and providing a safety valve for excess pressure below the crust.

Abraham Werner and

The German mineralogist and geologist Abraham Werner established a purely Neptunist school. He accepted the idea of geological succession in sedimentary deposits but did not develop its historical implications since he classified rocks by mineral content rather than fossils. Secularizing earlier theories based on the biblical flood, Werner held that rock strata formed from a universal primeval ocean, which produced four types of rocks by sequential processes. Primitive rocks, such as granite, crystallized out of the primeval ocean and contained no fossils. Transitional rocks, such as micas and slate, contained only a few fossils. Sedimentary rocks such as coal and limestone were next and were rich in fossils. Derivative rocks such as sand and clay formed from the other three by processes of weathering. Werner believed that volcanoes resulted from the burning of underground coal and were not an important geological force.

Although Werner's theory about the origin of sedimentary rocks was largely upheld, most other rocks were eventually shown to have an igneous origin from a molten state. This idea was developed by the Plutonist school of geology, which stressed the geological activity of the internal heat of the Earth, in addition to the volcanic eruptions of the Vulcanists. This view was developed by the Scottish amateur geologist James Hutton in his Theory of the Earth (1795). Hutton believed that the geological forces seen in the present operated in the same way and at the same rate in the Earth's past and that this principle should be the basis of geological explanation: The present is the key to the past.

Hutton's “uniformitarian principle” contrasted with Werner's idea of a primeval ocean, which involved catastrophic events confined to the past and unobservable in the present. Hutton carefully observed the slow and steady erosion of the land as rivers carried silt into the sea. He examined the weathered beds of gravel, sand, and mud brought down by the rivers, as well as the crystalline granites of the Scottish mountains. He concluded that sedimentary rocks formed from beds of mud and sand compressed by overlying seas and heat pressure from below, while crystalline rocks came from molten material inside the Earth brought to the surface by volcanic action.

Developing the idea that the interior of the Earth is molten, Hutton suggested that molten rock pushes into cracks beneath the Earth's crust, tilting up sedimentary strata and solidifying to form granites. Thus mountains were built with a crystalline core and sedimentary surface. This principle of injection was apparent in some granite intrusions into crevices in sedimentary rocks above, indicating that the granite was younger. The existence of granites of differing ages was contrary to Werner's assumptions. In some cases, Hutton found horizontal sedimentary strata covering tilted strata near the base of mountains, suggesting long periods since the strata had tilted. The Earth's age appeared so great that catastrophic events did not seem necessary to account for its surface features.

Cuvier's Theory Introduces Catastrophism

Although these uniformitarian ideas found some early support, it was not enough to overcome religious objections to a theory that required such an ancient Earth, delaying its eventual acceptance. In France, Georges Cuvier opposed Hutton's idea of slow geological processes with his theory of catastrophism in the introduction to his Researches on Fossil Bones (1812). Since there was no apparent continuity between successive strata and their fossils, he believed that a series of catastrophic floods must have occurred—rather than continuous forces—with each flood wiping out many species and eroding the Earth. These catastrophes also tilted strata left by earlier floods, ending with Noah's flood some six thousand years ago. Cuvier's catastrophism applied Neptunism to the vast time scale of Hutton. His influence delayed the acceptance of both biological and geological ideas of evolution in France for several decades.

In England and France, the study of strata was made easier by many well-exposed horizontal layers rich in fossils. These were systematically studied in France by Cuvier and in England by William Smith, who discovered in 1793 that each stratum had its own characteristic form of fossils. Their work revealed that strata near the surface were younger than those farther down, and a history of life-forms could be worked out from their fossils. Further stratigraphic studies by Adam Sedgwick and Roderick Murchison identified the Cambrian series of strata with the oldest fossil-bearing rocks, the Silurian series with the earliest land plants, and the Devonian series dominated by fish fossils.

The discoveries of this “heroic age of geology” (1790-1830) were summarized by the Scottish geologist Charles Lyell. Reviving Hutton's uniformitarian ideas, Lyell published three volumes entitled The Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface by Reference to Causes Now in Operation (1830-1833). Assuming indefinitely long periods of time, he insisted that geological forces had always been the same as they are now. Yet few of Lyell's contemporaries accepted his ideas before Charles Darwin developed them in his theory of organic evolution. The combined influence of Lyell and Darwin caused many scientists to shift away from Cuvier's catastrophism.

One of Cuvier's later associates, the Swiss-American naturalist Louis Agassiz, helped to modify the extreme uniformitarianism of Lyell. From the distribution of boulders and the grooves scratched on solid rock in the Swiss Alps, he showed in 1837 that Alpine glaciers had once stretched from the Alps across the plains to the west and up the sides of the Jura Mountains. In 1847, Agassiz accepted a position at Harvard University, and in North America, he found evidence that glaciers had also overrun that continent's northern half. Agassiz's Ice Age theory gradually won acceptance over more catastrophic flood theories, and evidence for several long ages of advancing and retreating ice over millions of years was eventually found.

Study of Earth History

By the end of the nineteenth century, uniformitarian logic had become the primary method of studying the history of the Earth's surface. Early in the twentieth century, the development of radioactive dating techniques confirmed the enormous age of the Earth, revealing some 4.6 billion years during which the same slow processes of erosion, eruption, sedimentation, and ground movement visible today could account for everything from the Grand Canyon to marine fossils in the Alps. Yet this very method has identified discontinuities and anomalies that reveal the importance of catastrophic events in Earth history. It now appears that the planet and its life-forms have been shaped by more than gradual processes still operating today. Evidence has accumulated that many sudden and violent events in the past had widespread consequences, including torrential flooding, massive volcanic activity, and huge asteroid impacts causing global disasters. A “new catastrophism” uses uniformitarian methods to show that past catastrophes may be the key to understanding the present.

An early attempt to revive catastrophism was made by American geologist J. Harlen Bretz in 1923 to explain certain landscape features. He suggested that some of the world's largest floods poured down the Columbia River Gorge from melting glaciers into the Pacific Ocean, scouring much of the Columbia Plateau down to bedrock and creating the Channeled Scablands of eastern Washington. His ideas were finally vindicated from aerial and satellite photographs. It was then shown that glacial Lake Missoula in Montana produced as many as seventy floods from about 15,000 to 12,000 years ago, matching legends of several Native American tribes in the Pacific Northwest. At that time, a glacial ice dam impounded a body of water some 400 kilometers long. Repeated emptying of Lake Missoula occurred when the ice dam floated and broke, releasing large amounts of water over at least forty hours. This deluge, which was some ten times the combined flow of all the world's rivers, removed soil as deep as 300 meters, inundating 7,800 square kilometers as deep as 106 meters.

More obvious catastrophic events are associated with volcanic activity. The most devastating volcanic eruption in recorded history was that of the Tambora volcano on Sumbawa Island, Indonesia, in 1815. The explosion killed 12,000 people, and another 82,000 died of starvation and disease. Tambora ejected so much volcanic ash into the stratosphere that Europe and North America experienced a year without a summer. Snow blanketed New England in June, and frosts blighted crops throughout the growing season.

Much larger volcanoes changed the landscape in prehistoric times. Volcanic activity in the Yellowstone region began about two million years ago as the continental crust moved westward. Subterranean melting of the crust produced a large underground reservoir of magma that resulted in three major explosions over one million years. The first produced one of the largest eruptions to occur on the Earth. After the roof of the magma reservoir collapsed, it subsided hundreds of meters, producing a caldera (giant crater) that covered an area of nearly 3,000 square kilometers. The volcanic ash canopy from the last eruption annihilated life over much of the western United States, and its fallout is preserved in strata from California to Kansas.

Other discoveries have revealed that asteroid or comet impacts are the probable source of even more widespread annihilation of life and may be associated with extensive volcanic activity. In 1958, the Estonian astrophysicist Ernst Öpik suggested that a sufficiently large asteroid collision could penetrate the continental crust, triggering the formation of huge areas of lava floods such as the Deccan Traps in western India and the Columbia River Plateau in the Pacific Northwest. In 1973, the American chemist Harold C. Urey proposed that a comet collision could cause sufficient heating of the biosphere to explain global extinctions. More recently, University of Montana geologists have shown that an asteroid impact seventeen million years ago could account for the immense lava flows of the Columbia River Plateau, spreading as far as 500 kilometers from their source to form the largest volcanic landform in North America. As the North American continental plate moved westward, the resulting hot spot shifted to form the Yellowstone volcanic region.

In 1980, a team of physicists and geologists headed by Luis Alvarez and his son Walter discovered that the thin global sediment that separates the end of the Cretaceous era (age of dinosaurs) from the Tertiary era (age of mammals) contained anomalous quantities of the element iridium, rare on the earth but common in meteorites. They suggested that this K-T boundary layer, dated at sixty-five million years ago, was evidence of an asteroid collision that ejected enough matter into the atmosphere to produce a “cosmic winter,” killing the dinosaurs and many other species. Their estimate of at least a ten-kilometer asteroid was confirmed in 1990, when a 200-square-kilometer crater was identified in the Yucatán region of Mexico, dating from sixty-five million years ago. Such a collision could have produced shock waves that came to a focus on the opposite side of the Earth, explaining the sixty-five-million-year-old eruptions that formed the Earth's largest lava fields in the Deccan Traps. Satellite surveys have revealed over 150 large but weathered craters on the Earth called astroblemes.

Principal Terms

asteroid: one of the numerous small rocky bodies bigger than about ten meters in size orbiting the sun, mostly between Mars and Jupiter; some, however, cross Earth's orbit

crater: an abrupt circular depression formed by extrusion of volcanic material or by the impact of an asteroid or meteorite

crust: the outermost solid layer or shell surrounding the Earth

fossil: naturally preserved remains or evidence of past life, such as bones, shells, casts, and impressions

geological column: the order of rock layers formed during the Earth's history

meteorite: a fragment of an asteroid that survives passage through the atmosphere and strikes the surface of the Earth

stratigraphy: the study of rock layers to determine the sequence of layers and the information it provides on the geological history of a region

uniformitarianism: the doctrine that geological events are caused by natural and gradual processes operating over long periods

volcanism: the processes by which magma is transferred from the Earth's interior to produce lava flows on the surface and the ejection of gases and ash into the atmosphere

Bibliography

Bowler, Peter J. Evolution: The History of an Idea. Reprint 2020, University of California Press, 2020.

Clube, Victor, and Bill Napier. The Cosmic Winter. Basil Blackwell, 1990.

Grotzinger, John, and Tom Jordan. Understanding Earth. 8th ed., Macmillan Learning, 2020.

Lewis, John S. Rain of Iron and Ice. Addison-Wesley, 1996.

Lucas, Spencer G. Dinosaurs: The Textbook. 7th ed., McGraw-Hill, 2022.

Meade, C. Elmon. Adam & Eve’s Ashes: Magnetic Pole Shift, Ancient Prophecy, and Catastrophism. BookBaby, 2023.

Moynihan, Thomas. Spinal Catastrophism: A Secret History. 2nd ed., Urbanomic Media Ltd, 2020.

Nemeh, Katherine H., and Jacqueline L. Longe. The Gale Encyclopedia of Science. 6th ed., Gale, a Cengage Company, 2021.

Rampino, Michael. “Darwin's Error? Patrick Matthew and the Catastrophic Nature of the Geological Record.” Historical Biology, vol. 23, 2011, pp. 227-30.

Roberts, Jason. Every Living Thing: The Great and Deadly Race to Know All Life. Random House, 2024.

Steel, Duncan. Rogue Asteroids and Doomsday Comets. John Wiley & Sons, 1995.

Wicander, Reed, and James S. Monroe. Historical Geology. 8th ed., Brooks/Cole, Cengage Learning, 2016.