T. Rex and the Crater of Doom

Nonfiction | Book | Adult | Published in 1997

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Background

Chapter Summaries & Analyses

Foreword-Chapter 2

Chapters 3-5

Chapters 6-7

Key Figures

Themes

Index of Terms

Important Quotes

Essay Topics

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Discussion Questions

Themes

The Scientific Process of Discovery

T. Rex and the Crater of Doom illuminates how the scientific process is central to discovery. Geologists use material evidence to form hypotheses that they strive to prove. The author demonstrates the tumultuous nature of scientific discovery, emphasizing how with each success that scientists enjoy, they inevitably face confusion and failure too. For example, Alvarez and his team searched excitedly for evidence that a supernova explosion could have killed the dinosaurs. They hoped that rocks from the KT boundary would contain plutonium-244, proving that a supernova had exploded near Earth at that time. While their first test suggested that plutonium-244 was present in the KT boundary rocks, the next test did not detect any plutonium, and the frustrated scientists had to go back to the drawing board to form a new theory: “A careful analysis of the experiment made it clear that the supernova hypothesis was dead […] We went home in the early morning dejected” (74).

In hindsight, Alvarez realizes how naive optimism fueled his early years in geological research: At the time he did not realize the constant struggle inherent in the scientific process, especially when engaged in new research:

As scientists, we are engaged in a conversation with Nature. We ask questions—like ‘Where is the crater?’—by making observations or performing experiments. And Nature answers, with the results of the observation or the experiment. It seems a straightforward thing to do, but in practice it is very difficult. A young scientist, just starting out, cannot imagine how hard it is to understand the real meaning of Nature’s answers, or how many ways there are to make mistakes and get fooled (85).

By discussing the constant trials of scientific research, Alvarez humbles himself (and other scientists) and suggests that curiosity and persistence are key traits for anyone who wants to make new discoveries in a professional scientific field. These observations provide a window into the geologists’ experience of trying to understand natural phenomena and its “intriguing puzzles” and generate new knowledge by using the scientific process. By persevering in this process and embracing multidisciplinary collaboration, Alvarez and his colleagues proved the Yucatan impact theory.

Rocks as Historical Records

In Alvarez’s recounting of his search for the “Crater of Doom,” he repeatedly highlights how rocks provide valuable insight into Earth’s ancient past. By studying rocks, geologists can understand the nature of Earth’s changes, including the forces that caused these changes and their consequences to Earth’s geography and species. Alvarez credits rocks with revolutionizing human understanding of Earth’s past:

It is only in the last couple of centuries that we have learned to decipher the events of this forgotten eternity and to write down its history. The key discovery was that history is written in rocks. Ex libro lapidum historia mundi - from the book of rocks comes the history of the Earth (18-19).

By emphasizing how geologists rely on rocks as historical records, Alvarez encourages readers to broaden their own perspective on rocks, which he argues are a revealing and important part of both nature and history. Rather than being stagnant, Alvarez portrays rocks as an ever-changing natural feature created by various geological processes and one that deserves appreciation:

More people are fascinated with plants and animals than are drawn to rocks, because plants and animals are living and dynamic, while rocks seem to lie there inert and unchanging. Rocks do change, but usually so slowly that few people notice the changes. It is precisely this sluggish, nearly static character that makes them good recorders of Earth history. Rocks remember the past (19).

Alvarez details how rocks record and preserve precious clues to how Earth formed and developed over millions of years. As the only remains from these ancient time periods, rocks help geologists understand both gradual and catastrophic changes in Earth’s history. The author’s descriptions help convey the wide variety of physical clues that rocks contain about the past, from fossilized animal remains to mineral and metal content as well as a record of both gradual and sudden environmental changes. Alvarez describes his excitement at finding a wealth of historical information encoded in rock layers at the Yucatan crater site: “We scrambled over the rocks, shouting out one discovery after another […] ‘Look at the current bedding in this sand!’ ‘Hey—this bed is packed with spherules!’ ‘What’s all this fossil wood doing in these deep-water sediments?!’” (116).

In researching these rock layers, Alvarez and his team compiled substantial and compelling evidence of an asteroid impact in the late Cretaceous period. Some of the most valuable clues Alvarez collected in his samples were rock features such as spherules, shocked quartz, and melted glass. Foraminifera, or fossilized shelled sea creatures, were likewise important indicators of a mass extinction. Alvarez describes how he interpreted the foraminifera in the rock layers to deduce that a mass extinction event occurred: “Above this complicated […] boundary bed, the deposition of quiet-water marls resumed as if nothing had happened—except that most of the species of foraminifera that had flourished in the surface water […] were now extinct” (120). He adds, “It would be hard to imagine a clearer testimonial to the KT boundary impact” (120). By detailing the vast diversity of information encoded in the world’s rock layers, Alvarez urges respect for the “book of rocks” (19) and the historical details they hold.

The Role of Catastrophes in Earth’s History

Alvarez’s book examines the two predominant schools of thought about Earth’s history in the field of geology throughout the 19th and 20th centuries: uniformitarianism (gradual change over eons) and catastrophism (sudden, violent change). In detailing geologists’ understanding of the Yucatan impact and its enormous consequences for Earth and its species, Alvarez argues that catastrophic events have played just as important a role in Earth’s development as gradual change. He thoroughly contextualizes both catastrophism and uniformitarianism, showing how early geologists embraced catastrophism as an explanation for how Earth could have developed such distinct landforms in what they assumed was a short period of time. Once geologists rejected Biblical timelines for Earth history, however, they embraced uniformitarianism, claiming that the world and its lifeforms have always developed incrementally over time. Alvarez acknowledges the veracity of most of this theory, which Charles Darwin promoted. However, he critiques the way that many geologists clung to gradualist views so intently that they summarily rejected any catastrophic theory. Alvarez chastises this close-mindedness, writing that many geologists “explained away or ignored” (59) evidence of catastrophic events. He laments, “Gradualism had become a dogma” (59).

The author’s impact theory changed not only how geologists understood the late Cretaceous dinosaur extinction, but also their general perspective on Earth’s history. By showing that the Yucatan impact likely triggered a mass extinction event that changed Earth forever, Alvarez and other geologists challenged their gradualist colleagues to reconsider their position:

With the KT crater found at last, the kind of hard-core uniformitarianism which automatically rejects all inferences of catastrophic events was dead. Though no serious scientist doubts that most Earth change is gradual, geologists are now free to explore the occasional catastrophic events which have punctuated Earth history (138).

Alvarez’s analysis of the Yucatan impact clearly demonstrates how these catastrophic events can reshape Earth and its ecosystems, as he describes the destructive capacity of the Yucatan asteroid impact. He explains, “In the zone where bedrock was melted or vaporized, no living thing could have survived. Even out to a few hundred kilometers from ground zero, the destruction of life must have been nearly total” (10). Once the asteroid had hit, Alvarez explains that the heat it generated would have destroyed nearby areas: “Entire forests were ignited, and continent sized wildfires swept across the lands” (11). Next, the impact generated a tsunami that crashed ashore. Alvarez highlights this wave’s destructive power:

As this deluge crashed onto the coast, it not only ripped apart whole forests, but it shook the continental margin so violently that huge volumes of sediment were mobilized into submarine landslides which flowed down into the deep Gulf” (12).

The author explains how this lethal catastrophe transformed Earth from a lively planet to a place of death and suffering: “Where only the day before there had been fertile landscapes, full of animals and plants of all kinds, now there was a vast, smoldering netherworld, mercifully hidden from view by black clouds of roiling smoke” (12). These vivid and detailed descriptions illustrate the force with which catastrophic events have played a key role in shaping Earth and how the planet and its life forms would be wildly different today had the Yucatan impact not happened.