Catastrophe Theory Reading Answers, IELTS Passage

Catastrophe Theory Reading Answers: The IELTS Reading passage "Catastrophe Theory" is a frequently featured topic that evaluates a candidate's ability to understand complex scientific concepts and historical perspectives. The questions typically cover formats like Note Completion, Matching Information, and Multiple-Choice Questions. Practicing this passage can help students become familiar with similar question patterns and enhance their comprehension skills. Regular practice will also improve the ability to identify key details and develop effective reading strategies, ultimately boosting overall IELTS exam 2025 performance.

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Catastrophe Theory Reading Answers Passage

Catastrophe theory

1. In the late eighteenth and early nineteenth centuries, the popular theory among Earth scientists was that a number of major catastrophes had taken place over a relatively short period of time to give Earth its shape. French geologist Baron Georges Cuvier introduced this idea, which was later coined the "Catastrophe Theory." Proponents of the catastrophe theory used fossilized creatures and the faunal changes in rock strata to support their beliefs that major events such as volcanoes had occurred on a worldwide scale. The catastrophe theory was used to support the notion that Earth's history was not a relatively long one.
2. In response to the catastrophe theory, a handful of Earth scientists searched for explanations that would provide a better scientific basis for Earth's geology. James Hutton, the father of geology, is best known for his gradualist theory, a paradigm that became known as "Uniformitarianism." Hutton published the theory of the Earth in 1795, after which many other geologists including Charles Lyell, adopted the idea that small changes on Earth occurred over a large expanse of time. Uniformitarianism rejected the idea that cataclysmic events could shape the Earth so quickly, and instead proposed the theory that the key to the present is the past. The term deep time was used to describe the span in which gradual geological processes occurred, especially the formation of sedimentary rock. Charles Darwin later based his work on the idea, by developing his theory of evolution.
3. The majority of paleontologists and geologists adopted the gradualist theory of Earth's history for more than 100 years. In 1980, a discovery in Italy gave scientists a reason to reconsider the discarded theories of catastrophism. Geologist Walter Alvarez discovered a clay layer in the K-T boundary that intrigued him. The K-T boundary refers to the layer of Earth between the Cretaceous and Tertiary periods. The geologist with the help of his father Luis Alvarez, a prominent physicist, analysed the clay for heavy metals. After careful examination, the clay was found to contain high levels of iridium. Samples taken from the K-T boundary in other parts of the world were examined, with the same findings.
4. The Alvarez group wrote a historic paper that applied the catastrophe theory to their discovery. According to their hypothesis, the iridium in the K-T boundary was caused by an asteroid or a comet that hit Earth near the end of the Cretaceous period, over 65 million years ago. They also proposed that the impact would have raised enough dust to block the sun and cool Earth, which in turn would have prevented photosynthesis. This chain reaction would have led to the extinction of plants and animals. The main reason that the Alvarez theory took hold so quickly in both the world of science and the public realm, was that it could account for the extinction of the dinosaurs at the end of the Cretaceous period. The acceptance of this theory was widespread, even before the discovery in 1990 of a 180-kilometer crater in Mexico's Yucatan Peninsula, a potential piece of evidence of the asteroid impact.
5. Events that have occurred on Earth in the last 100 years or more have proved to geologists that not all processes are gradual. Major rivers have flooded areas in a matter of days, and volcanoes have erupted, causing mass devastation. The eruption of Mount St. Helens was proof of how a catastrophe could easily change the Earth's landscape. Modern research on fossils even supports the theory of a marine catastrophe, not unlike the legends and stories among many peoples of great floods. Some scientists believe that animal remains found within the layers of sedimentary rock may have been casualties of such a flood. Sedimentary rock is made up of layers such as sandstone and limestone and is created by water movement. In addition, some scientists propose that the glacial ice sheet that once spread out across North America melted catastrophically rather than having a slow glacial retreat. Deep erosion up to 100 meters wide was discovered along the bottom of some of the Great Lakes. Within the gullies, layers of periodic sediment point to catastrophic melting.
6. Though there is little debate that catastrophic events caused the mass extinction of several of Earth's species, namely the dinosaurs, geologists still question whether asteroids, volcanoes, or other natural disasters were the cause. The idea that the moon was formed as a result of catastrophic events is a related field of study and one that has been debated for decades.

Catastrophe Theory Reading Answers Sample Questions

IELTS Reading Note Completion (Q. 1–6)

Complete the notes below.
Write NO MORE THAN THREE WORDS AND/OR A NUMBER for each answer.

1. The theory introduced by Baron Georges Cuvier in the late eighteenth century is known as the __________.
2. The idea that small geological changes occur over a long period of time is called __________.
3. The term "deep time" refers to the period over which __________ processes take place.
4. The clay layer in the K-T boundary was found to contain high levels of __________.
5. According to the Alvarez theory, the asteroid impact blocked sunlight and prevented __________.
6. The discovery of a 180-kilometer-wide crater in __________ supported the Alvarez theory.

IELTS Reading Matching Information (Q. 7–13)

Match the following statements (7–13) with the correct paragraphs (A–E) in the passage.
Write the correct letter, A–E, in the boxes provided.

7. The discovery that revived interest in the catastrophe theory.
8. The idea that Earth's shape resulted from major, rapid events.
9. Explanation of the gradualist theory and how it shaped geological understanding.
10. Reference to an important crater discovery that supported the Alvarez theory.
11. Modern examples of how sudden events have shaped Earth's landscape.
12. A theory explaining the origin of the moon.
13. Mention of fossil evidence supporting catastrophic events.

IELTS Reading Multiple-Choice Question (Q. 14)

Choose the correct letter A, B, C or D.

Why was the Alvarez theory widely accepted by scientists and the public?
A. It was supported by Charles Darwin’s theory of evolution.
B. It explained why the dinosaurs went extinct.
C. It was confirmed by the discovery of a meteorite.
D. It supported the uniformitarianism theory.

Catastrophe Theory Reading Answers with Explanations 

1. Answer: Catastrophe Theory

• Location: Paragraph 1

• Reference: "French geologist Baron Georges Cuvier introduced this idea, which was later coined the 'Catastrophe Theory.'"

• Explanation: The passage clearly states that the theory introduced by Cuvier was called the Catastrophe Theory.

2. Answer: Uniformitarianism

• Location: Paragraph 2

• Reference: "James Hutton, the father of geology, is best known for his gradualist theory, a paradigm that became known as 'Uniformitarianism.'"

• Explanation: The gradualist theory introduced by James Hutton was called Uniformitarianism.

3. Answer: Gradual geological

• Location: Paragraph 2

• Reference: "The term deep time was used to describe the span in which gradual geological processes occurred."

• Explanation: "Deep time" refers to the long period over which small geological changes take place.

4. Answer: Iridium

• Location: Paragraph 3

• Reference: "After careful examination, the clay was found to contain high levels of iridium."

• Explanation: The clay layer in the K-T boundary was discovered to have high levels of iridium.

5. Answer: Photosynthesis

• Location: Paragraph 4

• Reference: "They also proposed that the impact would have raised enough dust to block the sun and cool Earth, which in turn would have prevented photosynthesis."

• Explanation: The asteroid impact caused a blockage of sunlight, stopping the process of photosynthesis.

6. Answer: Mexico's Yucatan Peninsula

• Location: Paragraph 4

• Reference: "The acceptance of this theory was widespread, even before the discovery in 1990 of a 180-kilometer crater in Mexico's Yucatan Peninsula."

• Explanation: The crater that supported the Alvarez theory was found in Mexico's Yucatan Peninsula.

7. Answer: C

• Location: Paragraph 3

• Reference: "In 1980, a discovery in Italy gave scientists a reason to reconsider the discarded theories of catastrophism."

• Explanation: The discovery of the K-T boundary revived interest in the catastrophe theory.

8. Answer: A

• Location: Paragraph 1

• Reference: "The popular theory among Earth scientists was that a number of major catastrophes had taken place over a relatively short period of time to give Earth its shape."

• Explanation: The idea that Earth's shape was formed by rapid catastrophic events supports the catastrophe theory.

9. Answer: B

• Location: Paragraph 2

• Reference: "Hutton published the theory of the Earth in 1795, after which many other geologists including Charles Lyell, adopted the idea that small changes on Earth occurred over a large expanse of time."

• Explanation: This explains the theory of gradualism and its influence on geology.

10. Answer: D

• Location: Paragraph 4

• Reference: "The acceptance of this theory was widespread, even before the discovery in 1990 of a 180-kilometer crater in Mexico's Yucatan Peninsula."

• Explanation: The crater discovery supported the Alvarez theory about the asteroid impact.

11. Answer: E

• Location: Paragraph 5

• Reference: "Events that have occurred on Earth in the last 100 years or more have proved to geologists that not all processes are gradual."

• Explanation: Modern natural disasters, like volcanic eruptions and floods, demonstrate that catastrophic events shape Earth's landscape.

12. Answer: E

• Location: Paragraph 6

• Reference: "The idea that the moon was formed as a result of catastrophic events is a related field of study and one that has been debated for decades."

• Explanation: The passage mentions that the moon’s formation is linked to catastrophic events.

13. Answer: E

• Location: Paragraph 5

• Reference: "Modern research on fossils even supports the theory of a marine catastrophe."

• Explanation: Fossil evidence suggests that catastrophic events like floods shaped the Earth.

14. Answer: B. It explained why the dinosaurs went extinct.

• • Location: Paragraph 4

  • Reference: "The main reason that the Alvarez theory took hold so quickly... was that it could account for the extinction of the dinosaurs."

  • Explanation: The Alvarez theory was widely accepted because it explained the extinction of the dinosaurs, which was a major unresolved mystery in science.

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