Cataclysms

A New Geology for the Twenty-First Century

Michael R. Rampino

• Publisher: Columbia University Press
• Year: 2017
• eBook ISBN: 9780231544870
• Topic: Ciencias físicas
• Subtopic: Evolución

In 1980, the science world was stunned when a maverick team of researchers proposed that a massive meteor strike had wiped the dinosaurs and other fauna from the Earth 66 million years ago. Scientists found evidence for this theory in a "crater of doom" on the Yucatán Peninsula, showing that our planet had once been a target in a galactic shooting gallery. In Cataclysms, Michael R. Rampino builds on the latest findings from leading geoscientists to take "neocatastrophism" a step further, toward a richer understanding of the science behind major planetary upheavals and extinction events.

Rampino recounts his conversion to the impact hypothesis, describing his visits to meteor-strike sites and his review of the existing geological record. The new geology he outlines explicitly rejects nineteenth-century "uniformitarianism," which casts planetary change as gradual and driven by processes we can see at work today. Rampino offers a cosmic context for Earth's geologic evolution, in which cataclysms from above in the form of comet and asteroid impacts and from below in the form of huge outpourings of lava in flood-basalt eruptions have led to severe and even catastrophic changes to the Earth's surface. This new geology sees Earth's position in our solar system and galaxy as the keys to understanding our planet's geology and history of life. Rampino concludes with a controversial consideration of dark matter's potential as a triggering mechanism, exploring its role in heating Earth's core and spurring massive volcanism throughout geologic time.

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Catastrophism Versus Gradualism

Looking back dispassionately into the history of geology it is interesting to observe how deeply conservatism has become entrenched.

Alexander du Toit, Our Wandering Continents

I decided to become a geologist when I was about seven years old. The mother of a schoolmate took us to the American Museum of Natural History. Like Stephen Jay Gould, I was impressed by the amazing dinosaur skeletons on the fourth floor of the museum, but the stunning mineral and gem displays on the first floor also fascinated me. Various rocks and minerals collected from vacant lots and parks near my home in Brooklyn already occupied an entire bookshelf in my room. The museum collection showed me that beautiful mineral specimens occurred all over the globe, which more than kindled my other great desire, ignited by my love of maps and stamp collecting, to travel to faraway places in pursuit of rocks and fossils. Around the same time, my grandfather gave me a book on astronomy, with great pictures of galaxies and nebulae. I was captivated, and a little fearful, contemplating Earth’s place in infinite space, but the nighttime sky in New York City was not conducive to astronomical study.

In school, we built volcanoes using glycerol and potassium permanganate. (Such a thing would not be possible in current classrooms; volcanoes are now safely made with vinegar and baking soda.) While other kids got chemistry sets, I got a geology set, with lots of minerals and the apparatus needed to test their various properties. But I ached to know more about geology. In a search for geology books at the local secondhand bookstore, the best I could do at the time was an ancient copy of The Geological Story Briefly Told (1875), by James Dwight Dana (1813–1895; figure 1.1). Unknown to me, Dana was the preeminent American geologist of his time. His Manual of Geology (1863) was a widely used geology textbook in the second half of the nineteenth century, going through several editions.

FIGURE 1.1 James Dwight Dana (1813–1895), author of The Geological Story Briefly Told.

Dana, a professor of geology at Yale University, came from a long line of missionaries and educators. As a young man, from 1838 to 1842, he explored the Pacific with the Wilkes Expedition, and he published articles on coral reefs and coral islands, in parallel with Charles Darwin’s early voyages and publications. Later, in the 1880s, he led the first geological studies of the volcanoes of Hawaii.

I recently went back to my copy of Dana’s book (I still have it), which is intended for “the general reader and beginners in the sciences.” As I turned its yellowed pages, I was struck by something that I had not fully taken into account during my early readings. Dana’s geology had strong theological underpinnings. Time and time again, he mixes descriptions of the workings of geologic processes with theological interpretations. In his view, all the geologic events in the past were guided by God and directed toward one goal: the appearance of humanity.

How had I missed this? I found it hard to believe that Dana was writing in 1875, sixteen years after the publication of Darwin’s Origin of Species. Surely, the introduction of natural selection should have dispelled the notion of directed evolution. But changes in scientific attitudes do not happen overnight. Handwritten notes by a student who had marked the margins of my book show that geology courses were still using Dana’s book until around 1900.

I had assumed that Dana was a world-class observer and scientist, and that the antiquated idea of geologic evolution as part of a miraculous process designed for the creation and benefit of humankind had been banished from the sciences by the time he published his book. Yet here was the famous Dana saying that all the world’s geologic processes through countless epochs were designed to make the planet suitable for Homo sapiens: “The world by gradual steps reached its present perfected state, suited in every aspect to man’s needs and happiness—as much so as his body; and it shows throughout the same Divine purpose, guiding all things toward the one chief end, Man’s material and spiritual good.”

Even in his later career, in 1885, Dana went so far as to publish Creation; or, the Biblical Cosmogony in the Light of Modern Science in an effort to reconcile geologic history with biblical accounts of creation. It is not surprising that Dana also opposed the idea of evolution: “Until the long interval is bridged over by the discovery of intermediate species, it is certainly unsafe to declare that such a line of intermediate species existed, and as unphilosophical as it is unsafe.” Dana’s writings show that, even into the late nineteenth and early twentieth centuries, some geologists were still reading the rocks with the goal in mind of conciliation between the geologic past and the tenets of Scripture and were still seeing the appearance of humans as the prime objective of millions of years of evolution.

When I was a graduate student at Columbia in the early 1970s, I studied historical geology with the famous Marshall Kay, who was in his sixties at the time. Kay attended university in the 1920s, so his teachers would have been students in the late nineteenth century, when ideas like Dana’s were still widespread in the science. Thus the teachers of my teachers were presented at university with a picture of geology very much tied to theological interpretations. The history of Earth was represented as a record of changing sea levels, with slow and steady transgressions and regressions of the seas over the continents. It is no wonder that geology was for a long time caught up with notions of the design of a peaceful world. The truth is that, in some ways, modern geology is really not so far from the geology of the late nineteenth century.

Geology is a relatively new science. It was introduced as a fixed term by Horace-Bénédict de Saussure only in 1779. It grew partly out of “natural theology,” as espoused by the theologian William Paley (1743–1805) in his famous essay Natural Theology, or Evidences of the Existence and Attributes of the Deity Collected from the Appearances of Nature (1802). His book, which was one of the most published of the nineteenth and twentieth centuries, presents a number of teleological and cosmological arguments for the existence of God. Natural theology was proposed as a way to explain the apparent design of the world and of living things, as part of God’s rational plan. It takes its motivation from the far older, overtly theological belief in the legibility of the “book of nature.” God reveals himself in Scripture and in the Creation. The book and the world thus offer two parallel texts. The first offers evidence of God’s direct intervention in human affairs. But if, in a more “enlightened” age, one comes to regard the Bible as simply allegorical, then it becomes possible nevertheless to find evidence of divine purpose working through the features of Earth in a manner capable of rational study. That there is also supposedly an “order” among living beings, from “lowest” to “highest” (that is, humans), and that we stand at the pinnacle of creation by virtue of having been given the gift of reason and the knowledge of our creator, offers further “evidence” of the same providential intention.

At the time, Christian doctrine held that Earth as we know it was created in six days. In the 1650s, Bishop James Ussher (1581–1656) of Ireland undertook the calculation of the life spans of the prophets in the Bible, and other information, with the goal of figuring out the exact date of Earth’s creation. The result—Sunday, October 23, 4004 B.C.E., at 9:00 A.M.—was subsequently inscribed in Bibles as the official Christian date of creation. The implications for the study of Earth were clear: if the world was only 6,000 years old and had been created in six days, then Earth had essentially no deep history, and any geologic changes must necessarily be of a recent and catastrophic nature.

The influential late-eighteenth-century German geologist Abraham Gottlob Werner (1749–1817; figure 1.2) of the Freiberg Mining Academy proposed that the geologic record could be derived from consideration of the expected series of materials rapidly precipitated from a primal world ocean, perhaps during the Great Flood. This explanation was readily compatible with Scripture. Werner used the universal ocean to explain the sequence of rock types—with the densest on the bottom and lighter rocks at the top—that he supposed to exist in all places on Earth in the same order. He explained the crystalline rock granite, which he believed formed the base of rock sequences all over the world, as a chemical precipitate, deposited from the alkaline floodwaters as they first receded. Overlying rocks were the result of the rapid settling of sediments according to their density, all of this taking place very quickly. Werner’s theory did not explain how to dispose of the excess water that once covered the world, but no matter.

FIGURE 1.2 Abraham Gottlob Werner (1749–1817) of the Freiburg Mining Academy.

Werner’s idea of rock deposition from a universal sea became known as Neptunism. It is often said that Werner was no field geologist. Had he been, he would have realized that his theoretical rock sequence was no more than that—in many places, granites can be seen to intrude older sedimentary rocks that show signs of intense heating. Furthermore, sediments of various types are found interbedded in no standard order, contrary to what Werner predicted.

These Neptunist views were challenged by the theory propounded by the Scot James Hutton (1726–1797; figure 1.3) of a machinelike, dynamic Earth, driven by subterranean heat, with grand geologic cycles of decay and renovation—representing the continuous interplay between the great forces of uplift and erosion—stretching back to the uncharted beginnings of geologic time. Hutton was a gentleman farmer and businessman. A member of the Scottish Enlightenment, Hutton discussed science and philosophy with the likes of Adam Smith, David Hume, and James Watt.

Hutton’s geological ideas were of the “Plutonist” school. He argued from close examination of hand specimens and outcrops that crystalline rocks such as granites and basalts were originally molten material that had forced its way up from deep below and intruded into previously existing rocks or erupted at the surface. He and his followers eventually provided unequivocal evidence for the once molten origin of what are now called igneous rocks—generated at high temperatures in Earth’s hot interior.

Moreover, Hutton was a gradualist who envisioned a world in which the results of slow and steady geologic processes such as erosion, deposition, and uplift accumulated over eons to create the major changes in geologic history. These long-term cyclic changes required periods of time much longer than 6,000 years. Thus Hutton is said to have discovered “deep time”—the countless ages represented in Earth history. His classic observations of outcroppings (figure 1.4), where he could see that marine sediments had been uplifted and deformed, only to be completely eroded and overlain by a newer set of strata, showed that incredibly long periods of time must be involved in geologic history.

FIGURE 1.3 James Hutton (1726–1797), author of Theory of the Earth.

Across the English Channel, French geologists and paleontologists of the early nineteenth century, led by Baron Georges Cuvier (1756–1830; figure 1.5) of the Jardin des Plantes in Paris (and often called the “father of vertebrate paleontology”), favored a catastrophist theory of geologic change. Cuvier was a brilliant comparative anatomist. With his colleagues, he carefully studied the fossils and layers of rock in the Paris Basin and reported empirical evidence for episodic catastrophic and sweeping changes. They found that the geologic record gave evidence of long periods of quiet alternating with brief times marked by the sudden disappearance of fossil species—mass extinctions of life. Cuvier’s catastrophist interpretation claimed that the extinctions were sudden and involved unknown, cataclysmic forces. He argued that “we shall seek in vain among the various forces which still operate on the surface of our earth, for causes compet...

Table of contents

• Cover
• Title Page
• Copyright
• Contents
• Acknowledgments
• Introduction
• 1. Catastrophism Versus Gradualism
• 2. Lyell’s Laws
• 3. The Alvarez Hypothesis
• 4. Mass Extinctions
• 5. Kill Curves and Strangelove Oceans
• 6. Catastrophism and Natural Selection: Charles Darwin Versus Patrick Matthew
• 7. Impacts and Extinctions: Do They Match Up?
• 8. The Great Dying: The End-Permian Extinctions
• 9. Catastrophic Volcanic Eruptions and Extinctions
• 10. Ancient Glaciers or Impact-Related Deposits?
• 11. The Shiva Hypothesis: Comet Showers and the Galactic Carousel
• 12. Geological Upheavals and Dark Matter
• Epilogue: What Does It All Mean? A New Geology
• Sources and Further Reading
• Index