TOEFL iBT | Reading | Earth’s Age

Boom! We’re back with a tough reading, and I’ll be covering it for you guys! In today’s full reading segment, we have the infamous Earth’s Age write up which is a total kick-ass. Here we go!

[1] One of the first recorded observers to estimate Earth’s relative age was the Greek historian Herodotus, who lived from approximately 480 B.C. to 425 B.C. He realized that the Nile River Delta was in fact made up of a series of sediment deposits built up as a result of continuous floods. He noted that individual floods deposit only thin layers of sediment, and he was then able to conclude that the Nile Delta had taken thousands of years to build up. More important than Herodotus’s calculations of the Earth’s age, which are in fact trivial in comparison with the actual age of Earth, was the idea that one could estimate ages of geologic features by determining rates of the processes responsible for such features, and that it was possible to assume the rates to be roughly constant over time. Similar applications of this concept were used time and time again in later centuries to estimate the age of the formation of rocks, in particular, layers of sediment that had compressed and cemented to form sedimentary rocks.

[2] It wasn’t until the 17th century that any further attempts were made to understand clues to Earth’s history through the rock record. Nicolaus Steno (1638–1686) was the first to work out the principles of the progressive depositing of sediment in Tuscany. However, it was the founder of modern geology, James Hutton (1726–1797), who was the first to learn that geologic processes recur naturally, a key insight. Forces associated with subterranean heat cause land to be uplifted into plateaus and mountain ranges. The effects of wind and water then break down the masses of uplifted rock, producing sediment that is transported by water downhill to then form layers in oceans, lakes, or even seashores. With time, the layers then become sedimentary rock. These rocks are then uplifted in the future to form new mountain ranges, which exhibit sedimentary layers (and the remains of life within those layers) of the earlier episodes of erosion and deposition.

[3] Hutton’s idea thus represents an amazing insight because its discovery was able to unite many individual phenomena and observations into a conceptual picture of Earth’s history. With the further assumption that these geologic processes were generally no more or less vigorous than they are today, Hutton’s examination of sedimentary layers led him to the realization that Earth’s history must be colossal, that geologic time is an abyss and human history a speck by comparison.

[4] After Hutton, many geologists tried to determine rates of sedimentation so as to estimate the age of Earth from the total length of the sedimentary, or stratigraphic record. The numbers estimated for the age of Earth at the turn of the 20th century were 100 million to 400 million years. These numbers underestimated the actual age by factors of 10 to 50 because much of the sedimentary record is missing in various locations and because there is a long rock sequence that is older than half a billion years that is far less well defined in terms of fossils and less well preserved.

[5] A variety of other methods used to estimate the Earth’s age fell short, and could be seen as defective determinations of the Sun’s age. German philosopher Immanuel Kant (1724–1804) recognized that chemical reactions could not supply the tremendous amount of energy flowing from the Sun for more than about a millennium. The age of the Sun based on the Sun’s energy coming from gravitational contraction was discovered by two physicists in the 19th century. Due to the force of gravity, the compression resulting in an object’s collapse must release energy. Ages for Earth were derived that were in the tens of millions of years, much less than the geologic estimates of the time.

[6] It was the discovery of radioactivity at the end of the 19th century that resulted in finally determining both the Sun’s energy source and the age of Earth. From the discovery of radioactivity came a wave of discoveries leading to radioisotopic dating. This then led to the realization that Earth must be billions of years old, and finally to the discovery of nuclear fusion as an energy source capable of supporting the Sun’s luminosity for that amount of time. By the 1960s, both analyses of meteorites and refinements of solar evolution models came together to settle on an age for the solar system, and hence for Earth, of 4.5 billion years.

Questions

1 According to paragraph 2, James Hutton was the first person to

  • work out standards of the dynamic saving of silt.
  • understand that geologic processes occur in repeating cycles
  • show the power of Earth’s warm inner core
  • comprehend pieces of information to Earth’s history through the stone record.

2 Which of the following best expresses the essential information in the highlighted sentence? Incorrect answer choices change the meaning in important ways or leave out essential information.

With the further assumption that these geologic processes were generally no more or less vigorous than they are today, Hutton’s examination of sedimentary layers led him to the realization that Earth’s history must be colossal, that geologic time is an abyss and human history a speck by comparison.

  • Hutton understood that if these geologic procedures have dependably happened at about the same rate as they do today, Earth’s history is tremendously long compared to mankind’s.
  • Hutton’s idea revealed vast knowledge by bringing together numerous individual questions and ideas into a theoretical picture of Earth’s history
  • Hutton’s examination of aggregate layers caused him to infer that geologic processes have been by and large the same as they are today throughout Earth’s long history.
  • Hutton’s examination of clastic layers resulted in a breakthrough, and his decisions about geologic procedures are among the most noteworthy in mankind’s history

3 .As indicated by passage 4, what happened when geologists at the turn of the twentieth century attempted to gauge Earth’s age?

  • They disregarded Hutton’s discoveries about rates of sedimentation and by doing so their calculations were off by a factor of 10 to 50.
  • Utilizing the sedimentary record, they were able to figure Earth’s proper age within 100 million to 400 million years.
  • They didn’t realize that a great part of the sedimentary record is missing and in this way, believed that Earth was substantially younger than it is in reality.
  • They didn’t effectively ascertain the rates of sedimentation which caused them to incorrectly presume that the age of the Earth is considerably younger than it ought to be.

4 The word ‘defective’ in paragraph 5 is closest in meaning to:

  • broken
  • late
  • unspecific
  • incorrect

5 For what reason is ‘gravitational contraction’ used in the entry?

  • To demonstrate that inquiries concerning the Sun’s vitality source were as intriguing to early researchers as inquiries regarding Earth’s age
  • To give prove that Hutton’s thoughts prompted an in material science and stargazing and also in geography
  • To refer to a strategy for assessing the age of the Sun that was utilized to decide Earth’s age
  • To clarify why there is such a lot of vitality spilling out of the Sun

6 As indicated by paragraph 5, Immanuel Kant perceived that the Sun’s vitality

  • was not possible through chemical reactions alone over a long period of time.
  • originated from powerful pressure resulting from gravity.
  • was to a great extent the consequence of synthetic responses that occurred over a time of over a thousand years.
  • was important to fuel the greater part of the concoction responses on Earth

7 As indicated by passage 6, which of the following isn’t valid about researchers latest estimate of Earth’s age?

  • It depends on data taken from the examination of shooting stars.
  • It is shockingly similar to estimates from the nineteenth century.
  • It is affirmed by sun based development models.
  • It puts the period of Earth at around 4 5 billion years.

8 Which of the following can be inferred from paragraph 6 about the formation of the solar system?

  • The Sun was already billions of years old when the planets were formed.
  • The planets closest to the Sun formed first.
  • Meteorites entered the solar system sometime after the planets were formed.
  • All parts of the solar system formed at approximately the same time.

9 Examine the four █ in the selection below and indicate at which block the following sentence could be inserted into the passage:


This thought came to be known as the rule of uniformitarianism, and Herodotus was just the first to apply it.

One of the first recorded observers to estimate Earth’s relative age was the Greek historian Herodotus, who lived from approximately 480 B.C. to 425 B.C. █ [A] He realized that the Nile River Delta was in fact made up of a series of sediment deposits built up as a result of continuous floods. █ [B] He noted that individual floods deposit only thin layers of sediment, and he was then able to conclude that the Nile Delta had taken thousands of years to build up. █ [C] More important than Herodotus’s calculations of the Earth’s age, which are in fact trivial in comparison with the actual age of Earth, was the idea that one could estimate ages of geologic features by determining rates of the processes responsible for such features, and that it was possible to assume the rates to be roughly constant over time. █ [D] Similar applications of this concept were to be used time and time again in later centuries to estimate the age of the formation of rocks, in particular, of layers of sediment that had compressed and cemented to form sedimentary rocks..

  • [A]
  • [B]
  • [C]
  • [D]

10 Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Deciding the period of Earth has been a troublesome issue ever of.

  •  
  •  
  •  
  • A.Herodotus endeavored to compute Earth’s age by watching residue stores, however, modem standards for evaluating Earth’s age from geologic procedures emerged from crafted by Steno and Hutton.
  • B.Gaps in the sedimentary record started to be perceived by Kant and were later clarified by physicists contemplating the amount of energy provided by the Sun.
  • C.Radio isotopic dating, made possible by the discovery of radioactivity, as well as the revelation of atomic fusion, cleared up misconceptions regarding as to Earth’s age and the source of the sun’s energy.
  • D. Hutton portrayed the impacts of wind and water on masses of inspired shake and was the first to propose that a significant part of the sedimentary record was missing because of disintegration.
  • E. Estimates of Earth’s age from the past were amazingly low in light of what we know today about the rates of geologic procedures, and evaluations of the Sun’s age and vitality source.
  • F. In the 1960s researchers moved from the investigation of shooting stars to refinements of sun-based advancement models and decided the age of the nearby planetary group to be no less than a billion years.

Answers on Next Page

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