Catastrophism

Catastrophism is the doctrine that Earth’s history has been dominated by cataclysmic events rather than gradual processes acting over long periods of time. For example, a catastrophist might conclude that the Rocky Mountains were created in a single rapid event such as a great earthquake rather than by imperceptibly slow uplift and erosion.

Catastrophism developed in the seventeenth and eighteenth centuries. A prominent British theologian, Bishop James Ussher (1581–1656) added together the ages of people in the Bible and calculated that Earth must have been created in 4004 BC. His calculation implied that all of the features of Earth’s surface must be less than 6,000 years old and were therefore formed as the result of violent upheavals or catastrophes. Current research, in contrast, suggests that Earth is about 4.5 billion years old. Baron Georges Cuvier (1769–1832), a French anatomist, tried to reconcile the fossil record with Biblical history. Cuvier stated that different groups of fossil organisms were created and then became extinct as the result of geologic catastrophes, the last of which was the great flood described in the Bible. Each catastrophe, according to Cuvier, killed the fossilized organisms and deposited the sediment that solidified into the rock surrounding the fossils.

A new concept, uniformitarianism, grew from the work of the Scottish geologist James Hutton (1726–1797) and eventually replaced catastrophism. Uniformitarianism is the doctrine that geologic processes operate at the same rates and with the same intensity now as they did in the past. Hutton suggested that Earth had a very long history that could be understood in terms of currently observable processes such as the weathering of rocks and erosion of sediment. Sandstone, for example, was formed by the same kinds of physical processes that form modern sandy beaches or deserts. Therefore, catastrophic events were not needed to explain Earth’s history. Geologists often summarize the idea of uniformitarianism with the phrase, “The present is the key to the past.”

The concept of catastrophism has been revived with the discovery of large meteorite impact structures and evidence of mass extinctions in the fossil record. The most notable of these events was the asteroid impact marking the boundary between the Cretaceous and Tertiary Periods about 65 million years ago, which coincides with the extinction of the dinosaurs. The resulting Chicxulub impact structure, located in the Gulf of Mexico near the Yucatan Peninsula, is approximately 120 mi (180 mi) wide and 1 mi (1.6 km) deep. It is thought that the crater was formed by the catastrophic impact of an asteroid 4–9 mi (6–15 km) in diameter. The impact produced a thin layer of clay that contains elements rare on Earth but abundant in meteorites, along with minerals that can only be formed under very high pressure. Soot within the clay also suggests that the impact triggered extensive wildfires, which may have acted with sulfate minerals pulverized in the impact, to slow photosynthesis and cause global cooling to occur. Clouds of dust may have darkened the atmosphere for weeks or months. Other large impact structures on Earth include a 100 mi (120 km) wide structure in Acraman, Australia, a 120 mi (200 km) wide structure near Sudbury, Ontario, Canada, and an 50 mi (85 km) wide structure in Chesapeake Bay, Virginia and Maryland. Meteor Crater, Arizona, is an example of a relatively small impact structure.

The recognition that Earth’s history has been punctuated by rare but catastrophic events such as asteroid impacts has led most geologists to abandon strict uniformitarianism in favor of a doctrine known as actualism. Actualism states that the laws of nature do not change with time and much of Earth’s history can be explained in terms of currently observable processes. It acknowledges, however, that rates of geologic change are not constant over long periods of time, and that there have been some catastrophic geologic events that are far beyond the range of human experience.

Catastrophism

Introduction

Catastrophism is the general concept that the history of Earth has been profoundly affected by sudden violent events. In the Biblical creationist view, these sudden, violent events are typically viewed as supernatural in origin and are global events of great devastation. In the modern holistic view of Earth history, catastrophism is viewed as the concept that sudden, violent, but entirely explicable events have occurred in Earth's past and may have had an effect upon the rock and fossil record of Earth. In this view, a catastrophe may have been, for instance, a colossal volcanic eruption, a comet or asteroid impact on Earth, the burst of a large glacial lake's dam, or a very powerful earthquake.

Catastrophism stands in contrast to a long-standing but somewhat simplistic view in geology, that Earth processes were more nearly uniform and gradual over geologic time (uniformitarianism). Careful geological research in many subfields of geology over many decades has shown that geological history may be characterized by episodes of uniform and gradual conditions, which in turn are punctuated by episodes with relatively sudden, violent events. In other words, the notion of catastrophes in Earth history is a sound one, but the notion that Earth history is largely one of profound catastrophe is not correct.

Historical Background and Scientific Foundations

Catastrophism as a point of view in geology was founded in the nineteenth century during a time when it was popular to invoke Biblical, supernatural explanations for geological features that were confounding to practitioners of the infant science of geology. One of the first generalizations coming out of catastrophism was the notion of a Biblical flood-related origin for such things as the separation of the continents, mass mortality in the fossil record, glacial erratic boulders and other features, and some aspects of inter-regionally distributed rock

formations. Catastrophism was generally closely associated with a young-Earth viewpoint, specifically that Earth was not more than a few thousand years old. Therefore, in order for the many features we see to exist, they must have all developed in a short time span, hence catastrophes as the key to understanding Earth history.

With the advent of the view of deep time (or vast geological history), an opposing viewpoint called uniformitarianism emerged. In this contrary view, Earth history is gradual and changes are uniform with time. The view of uniformitarianism was intended more as a counterpoint to catastrophism, but was taken quite literally for many decades. Today, both gradual and catastrophic origins of features and rock formations are embraced by geologists according to the interpretations of those features and rock formations warranted by the facts at hand.

Catastrophism and the Fossil Record

Some nineteenth-century paleontologists (scientists who study fossils) who were also catastrophists thought that episodes of mass extinction of fossil groups showed evidence of supernatural catastrophes. Today, we understand that some fossil groups disappeared over relatively short intervals of geologic time, but in each instance we can see evidence of readily explainable causes. Further, careful study shows that even the most seemingly instantaneous extinction event probably occurred over hundreds or perhaps thousands of years, thus showing that these apparent catastrophes were not so sudden. Over the evolutionary history of many fossil groups, it can be shown that the development of new species and the death of other ones is relatively sudden (but not instantaneous). This is called punctuated gradualism in evolution, and is thought to be the result of rapid shifts in the fossil group's environment.

Impacts and Issues

Modern catastrophism is held by many creationists and others who hold to what they consider to be a fundamentalist view of Earth history. For example, in the modern catastrophist view held by creationists, Earth history can be divided into pre-flood and post-flood epochs. All of Earth history is divided according to one catastrophic event. Modern catastrophists also hold to the young-Earth view that all of Earth history occurred in a few thousand years. In this sense, most of Earth's history had to be sudden and violent, or Earth had to be formed as we know it without any significant evolutionary history.

WORDS TO KNOW

EPOCH: Unit of geological time. From longest to shortest, the geological system of time units is eon, era, period, epoch, and stage. Epochs are generally about 500 million years in length.

GEOLOGIC TIME: The period of time extending from the formation of Earth to the present.

UNIFORMITARIANISM: Doctrine of geology promoted by English geologist Charles Lyell (1797–1895), asserting three assumptions: (1) actualism (uniform processes acting throughout Earth's history), (2) gradualism (slow, uniform rate of change throughout Earth's history), and (3) uniformity of state (Earth's conditions have always varied around a single, steady state). Uniformitarianism is often contrasted to castrophism. Modern geology makes use of elements of both views, acknowledging that change can be drastic or slow, and that while some processes operate steadily over many millions of years, others (such as asteroid impacts) may happen rarely and cause castatrophic, sudden changes when they do.

From a catastrophist point of view, the rapidity of modern climate change on Earth would be viewed as supporting evidence of interpreted climate changes in Earth's past that may have been relatively rapid. That modern climate change is relatively rapid is a view that is not out of step with modern scientific understandings.

See Also Abrupt Climate Change; Extinction; Geologic Time Scale.

BIBLIOGRAPHY

Books

Palmer, T. Catastrophism, Neocatastrophism and Evolution. Nottingham, UK: Nottingham Trent University, 1994.

Rudwick, M. J. S. The Meaning of Fossils. Chicago: University of Chicago Press, 1972.

Web Sites

Baker, Victor. “Catastrophism and Uniformitarianism: Logical Roots and Current Relevance in Geology.” Geological Society of London, 1998. < http://sp.lyellcollection.org/cgi/content/abstract/143/1/171> (accessed December 4, 2007).

David T. King Jr .

Catastrophism

Catastrophism is the argument that Earth's features—including mountains, valleys, and lakes—primarily formed and shaped as a result of the periodic but sudden forces as opposed to gradual change that takes place over a long period of time.

Although geologists may argue about the extent of catastrophism in shaping the earth, modern geologists interpret many formations and events as resulting from an interplay catastrophic and uniform forces that result in more slowly evolving change.

For example, according to strict catastrophe theory, one might interpret the origins of the Rocky Mountains or the Alps, as resulting from a huge earthquake that uplifted them quickly. When viewing the Yosemite Valley in California a catastrophist might not assert they were carved by glaciers , but rather the floor of the valley collapsed over 1,000 ft (305m) to its present position in one giant plunge. Strict catastrophic theory also argues for long periods of inactivity following catastrophic events.

In terms of modern geoscience, strict catastrophic theory (e.g., a world shaped by large single floods , or massive earthquakes) finds little evidence or support. Catastrophism developed in the seventeenth and eighteenth centuries when, by tradition and even by law, scientists used the Bible and other religious documents as a scientific documents.

For example, when a prominent theologian, Irish biblical scholar Bishop James Ussher in the mid-1600's work, Annals of the World, counted the ages of people in the Bible and proclaimed that Earth was created in 4004 b.c. (In fact, Ussher even pronounced an actual date of creation as the evening of October 22), geologists tried to work within a time frame that encompassed only around six thousand years. (Current research estimates Earth at 4.5 billion years old.) In its original form, catastrophism eventually fell from grace with the scientific community as they reasoned more logical explanations for natural history. A new concept, known as uniformitarianism , eventually replaced catastrophism. Uniformitarianism is the argument that mountains are uplifted, valleys carved, and sediments deposited over immense time periods by the same physical forces and chemical reactions in evidence today.

Modern catastrophism—increasingly popular since the late 1970s—argues evidence that catastrophic forces can have a profound influence on shaping Earth. For example, modern catastrophic theory argues that large objects from space (Asteroids , Comets , etc.) periodically collide with Earth and that these collisions can have profound effects on both the geology and biology of Earth. Based on the extrapolation of experimental data and the observation of large-scale events (e.g., major volcanic eruptions ), scientists speculate that when these objects strike, they clog the atmosphere with sunlight-blocking dust and gases, ignite forest fires, and trigger volcanism. One hypothesis advances that a large asteroid impact lead to the extinction of dinosaurs roughly 65 million years ago.

See also Cambrian Period; Fossil record; Fossils and fossilization; Geologic time; Historical geology; Impact crater; K-T event; Origin of life; Orogeny; Plate tectonics; Precambrian; Torino scale

Catastrophism

Catastrophism is the doctrine that Earth's history has been dominated by cataclysmic events rather than gradual processes acting over long periods of time. For example, a catastrophist might conclude that the Rocky Mountains were created in a single rapid event such as a great earthquake rather than by imperceptibly slow uplift and erosion .

Catastrophism developed in the seventeenth and eighteenth centuries. A prominent British theologian, Bishop James Ussher (1581–1656) added together the ages of people in the Bible and calculated that Earth must have been created in 4004 b.c. His calculation implied that all of the features of Earth's surface must be less than 6,000 years old and were therefore, formed as the result of violent upheavals or catastrophes. Current research, in contrast, suggests that the earth is about 4.5 billion years old. Baron Georges Cuvier (1769–1832), a French anatomist, tried to reconcile the fossil record with Biblical history. Cuvier stated that different groups of fossil organisms were created and then became extinct as the result of geologic catastrophes, the last of which was the great flood described in the Bible. Each catastrophe, according to Cuvier, killed the fossilized organisms and deposited the sediment that solidified into the rock surrounding the fossils.

A new concept, uniformitarianism , grew from the work of the Scottish geologist James Hutton (1726–1797) and eventually replaced catastrophism. Uniformitarianism is the doctrine that geologic processes operate at the same rates and with the same intensity now as they did in the past. Hutton suggested that Earth had a very long history that could be understood in terms of currently observable processes such as the weathering of rocks and erosion of sediment. Sandstone, for example, was formed by the same kinds of physical processes that form modern sandy beaches or deserts. Therefore, catastrophic events were not needed to explain Earth's history. Geologists often summarize the idea of uniformitarianism with the phrase, "The present is the key to the past."

The concept of catastrophism has been revived with the discovery of large meteorite impact structures and evidence of mass extinctions in the fossil record. The most notable of these events was the asteroid impact marking the boundary between the Cretaceous and Tertiary Periods about 65 million years ago, which coincides with the extinction of the dinosaurs. The resulting Chicxulub impact structure, located in the Gulf of Mexico near the Yucatan Peninsula , is approximately 120 mi (180 mi) wide and 1 mi (1.6 km) deep. It is thought that the crater was formed by the catastrophic impact of an asteroid 4–9 mi (6–15 km) in diameter. The impact produced a thin layer of clay that contains elements rare on Earth but abundant in meteorites and minerals that can only be formed under very high pressure . Soot within the clay also suggests that the impact triggered extensive wildfires, which may have acted with sulfate minerals pulverized in the impact, to slow photosynthesis and cause global cooling to occur. Clouds of dust may have darkened the atmosphere for weeks or months. Other large impact structures on Earth include a 100 mi (120 km) wide structure in Acraman, Australia , a 120 mi (200 km) wide structure near Sudbury, Ontario, Canada, and an 50 mi (85 km) wide structure in Chesapeake Bay, Virginia and Maryland. Meteor Crater, Arizona, is an example of a relatively small impact structure.

The recognition that Earth's history has been punctuated by rare but catastrophic events such as asteroid impacts has led most geologists to abandon strict uniformitarianism in favor of a doctrine known as actualism. Actualism states that the laws of nature do not change with time and much of Earth's history can be explained in terms of currently observable processes. It acknowledges, however, that rates of geologic change are not constant over long periods of time and there have been some catastrophic geologic events that are far beyond the range of human experience.

Catastrophism

In geology, catastrophism is the belief that Earth's features—including mountains, valleys, and lakes—were created suddenly as a result of great catastrophes, such as floods or earthquakes. This is the opposite of uniformitarianism, the view held by many present-day scientists that Earth's features developed gradually over long periods of time.

Catastrophism developed in the seventeenth and eighteenth centuries when tradition and even the law forced scientists to use the Bible as a scientific document. Theologians (religious scholars) of the time believed Earth was only about 6,000 years old (current scientific research estimates Earth to be 4.5 billion years old). Based on this thinking and the supernatural events described in the book of Genesis in the Bible, geologists concluded that fossils of ocean-dwelling organisms were found on mountain tops because of Noah's flood. The receding flood waters also carved valleys, pooled in lakes, and deposited huge boulders far from their sources.

Over the next 200 years, as geologists developed more scientific explanations for natural history, catastrophism was abandoned. Since the late 1970s, however, another form of catastrophism has arisen with the idea that large objects from space periodically collide with Earth, destroying life. Scientists speculate that when these objects strike, they clog the atmosphere with sunlight-blocking dust and gases. One theory holds that the most famous of these collisions killed off the dinosaurs roughly 65 million years ago.

[See also Uniformitarianism ]