Years before the advent of plate tectonics―the widely accepted theory, developed in the mid-1960's, the holds that the major features...
GMAT Reading Comprehension : (RC) Questions
Years before the advent of plate tectonics―the widely accepted theory, developed in the mid-1960's, the holds that the major features of Earth's surface are created by the horizontal motions of Earth's outer shell, or lithosphere―a similar theory was rejected by the geological community. In 1912, Alfred Wegener proposed, in a widely debated theory that came to be called continental drift, that Earth's continents were mobile. To most geologists today, Wegener's The origin of Continents and Oceans appears an impressive and prescient document, containing several of the essential presumptions underlying plate tectonics theory: the horizontal mobility of pieces of Earth's crust; the essential difference between oceanic and continental crust; and a causal connection between horizontal displacements and the formation of mountain chains. Yet despite the considerable overlap between Wegener's concepts and the later widely embraced plate tectonics theory, and despite the fact that continental drift theory presented a possible solution to the problem of the origin of mountains at a time when existing explanations were seriously in doubt, in its day Wegener's theory was rejected by the vast majority of geologists.
Most geologists and many historians today believe that Wegener's theory was rejected because of its lack of an adequate mechanical basis. Stephen Jay Gould, for example, argues that continental drift theory was rejected because it did not explain how continents could move through an apparently solid oceanic floor. However, as Anthony Hallam has pointed out, many scientific phenomena, such as the ice ages, have been accepted before they could be fully explained. The most likely cause for the rejection of continental drift―a cause that has been largely ignored because we consider Wegener's theory to have been validated by the theory of plate tectonics―is the nature of the evidence that was put forward to support it. Most of Wegener's evidence consisted of homologies―similarities of patterns and forms based on direct observations of rocks in the field, supported by the use of hammers, hand lenses, and field notebooks. In contrast, the data supporting plate tectonics were impressively geophysical―instrumental determinations of the physical properties of Earth garnered through the use of seismographs, magnetometers, and computers.
The author cites Hallam on the ice ages primarily in order to
1. Passage Analysis:
Progressive Passage Analysis
| Text from Passage | Analysis |
|---|---|
| Years before the advent of plate tectonics―the widely accepted theory, developed in the mid-1960's, the holds that the major features of Earth's surface are created by the horizontal motions of Earth's outer shell, or lithosphere―a similar theory was rejected by the geological community. | What it says: Before plate tectonics theory became accepted in the 1960s, geologists rejected a similar theory. What it does: Sets up a historical contrast - introduces the puzzle of why one theory was accepted while a similar earlier one was rejected. Source/Type: Historical fact Connection to Previous Sentences: This is the opening - establishes the basic timeline and mystery. Visualization: Timeline: Earlier rejected theory → 1960s plate tectonics accepted Reading Strategy Insight: This opening signals we'll be exploring a historical puzzle about scientific acceptance What We Know So Far: Two similar theories, different fates What We Don't Know Yet: What the earlier theory was, why it was rejected |
| In 1912, Alfred Wegener proposed, in a widely debated theory that came to be called continental drift, that Earth's continents were mobile. | What it says: In 1912, Wegener proposed continental drift theory - the idea that continents move. What it does: Identifies the "earlier rejected theory" from sentence 1. Source/Type: Historical fact Connection to Previous Sentences: This builds on sentence 1 by revealing what that "similar theory" was. This is clarification, not new complexity! Visualization: 1912: Wegener says continents move → 1960s: Plate tectonics accepted Reading Strategy Insight: Feel relieved here - we now have concrete details filling in the mystery from sentence 1. |
| To most geologists today, Wegener's The origin of Continents and Oceans appears an impressive and prescient document, containing several of the essential presumptions underlying plate tectonics theory: the horizontal mobility of pieces of Earth's crust; the essential difference between oceanic and continental crust; and a causal connection between horizontal displacements and the formation of mountain chains. | What it says: Modern geologists think Wegener's work was impressive and ahead of its time, containing key ideas that later became part of plate tectonics. What it does: Lists specific similarities between the two theories. Source/Type: Current scientific opinion Connection to Previous Sentences: This explains what "similar theory" means from sentence 1 - shows the theories weren't just similar, but remarkably similar. Visualization: Wegener's 1912 theory contained: Crust mobility + Oceanic vs continental differences + Movement creates mountains = Core of 1960s plate tectonics Reading Strategy Insight: This deepens the mystery - if the theories were so similar, why different outcomes? |
| Yet despite the considerable overlap between Wegener's concepts and the later widely embraced plate tectonics theory, and despite the fact that continental drift theory presented a possible solution to the problem of the origin of mountains at a time when existing explanations were seriously in doubt, in its day Wegener's theory was rejected by the vast majority of geologists. | What it says: Even though Wegener's theory was similar to plate tectonics AND offered solutions when other explanations were failing, geologists still rejected it. What it does: Restates and intensifies the puzzle from sentence 1 - makes the rejection seem even more puzzling. Source/Type: Historical fact with author's analysis Connection to Previous Sentences: This is NOT new information! It's the author helping us by restating the central mystery with more evidence of how puzzling it is. Visualization: Wegener's theory: ✓ Similar to accepted theory + ✓ Solved existing problems = ❌ Still rejected Reading Strategy Insight: Recognize this as reinforcement - the author is emphasizing how strange this rejection was |
| Most geologists and many historians today believe that Wegener's theory was rejected because of its lack of an adequate mechanical basis. | What it says: Today's experts think Wegener's theory was rejected because it didn't explain HOW continents could move. What it does: Introduces the conventional explanation for the rejection. Source/Type: Current expert consensus Connection to Previous Sentences: This finally offers an answer to the mystery built up in sentences 1-4. Visualization: Standard explanation: Wegener showed WHAT (continents move) but not HOW (mechanism) → Rejection Reading Strategy Insight: We're getting our first proposed solution to the puzzle. |
| Stephen Jay Gould, for example, argues that continental drift theory was rejected because it did not explain how continents could move through an apparently solid oceanic floor. | What it says: Gould specifically says the theory was rejected because it couldn't explain how continents move through solid ocean floor. What it does: Provides a concrete example that restates sentence 5 Source/Type: Specific expert's opinion (Gould) Connection to Previous Sentences: This builds on sentence 5 by giving us a specific example of the "lack of mechanical basis" - NOT new complexity, just illustration! Visualization: Gould's version: Continents need to move through solid ocean floor → No explanation how → Rejection Reading Strategy Insight: Feel confident here - this is just a concrete example of the previous sentence. |
| However, as Anthony Hallam has pointed out, many scientific phenomena, such as the ice ages, have been accepted before they could be fully explained. | What it says: Hallam argues that lack of explanation isn't always a barrier - ice ages were accepted without full explanation. What it does: Introduces doubt about the conventional explanation from sentences 5-6. Source/Type: Counter-argument from expert (Hallam) Connection to Previous Sentences: This contrasts with sentences 5-6. The "lack of mechanism" explanation might not be correct Visualization: Ice ages: No full explanation → Still accepted ≠ Wegener's theory: No mechanism → Rejected Reading Strategy Insight: The author is casting doubt on the standard explanation - preparing us for an alternative |
| The most likely cause for the rejection of continental drift―a cause that has been largely ignored because we consider Wegener's theory to have been validated by the theory of plate tectonics―is the nature of the evidence that was put forward to support it. | What it says: The author thinks the real reason for rejection was the TYPE of evidence Wegener used, and this has been overlooked because we now think he was right. What it does: Presents the author's main thesis - an alternative explanation for the rejection. Source/Type: Author's own argument Connection to Previous Sentences: This offers an alternative to the "lack of mechanism" explanation from sentences 5-6, building on Hallam's doubt in sentence 7. Visualization: Standard view: Mechanism problem → Rejection Author's view: Evidence type problem → Rejection Reading Strategy Insight: This is the author's main point - everything has been building to this alternative explanation |
| Most of Wegener's evidence consisted of homologies―similarities of patterns and forms based on direct observations of rocks in the field, supported by the use of hammers, hand lenses, and field notebooks. | What it says: Wegener's evidence was based on observing similar rock patterns using simple field tools. What it does: Describes the first type of evidence (Wegener's) in the author's comparison. Source/Type: Factual description Connection to Previous Sentences: This explains what "nature of evidence" means from sentence 8 - gives us the concrete details of Wegener's approach. Visualization: Wegener's evidence: Field observations + Simple tools (hammers, lenses, notebooks) → Pattern similarities Reading Strategy Insight: We're getting the first half of what will clearly be a contrast. |
| In contrast, the data supporting plate tectonics were impressively geophysical―instrumental determinations of the physical properties of Earth garnered through the use of seismographs, magnetometers, and computers. | What it says: Plate tectonics evidence used sophisticated instruments like seismographs and computers to measure Earth's physical properties. What it does: Completes the evidence-type comparison started in sentence 9 Source/Type: Factual description Connection to Previous Sentences: This is the second half of the contrast - showing the difference in evidence types that the author believes explains the different receptions. Visualization: Wegener (1912): Field tools → Visual patterns → Rejected Plate tectonics (1960s): High-tech instruments → Geophysical data → Accepted Reading Strategy Insight: The passage completes its argument - rejection wasn't about mechanism, but about evidence style What We Know Now: Complete alternative explanation for why similar theories had different fates Final Takeaway: Evidence presentation style, not theoretical content, determined scientific acceptance |
2. Passage Summary:
Author's Purpose:
To challenge the common explanation for why Wegener's continental drift theory was rejected and offer an alternative explanation based on the type of evidence used.
Summary of Passage Structure:
The author builds their argument by setting up a historical puzzle and then resolving it with a new explanation:
- First, the author presents a puzzling historical contrast - an earlier theory similar to plate tectonics was rejected while plate tectonics itself was later accepted
- Next, the author identifies this earlier theory as Wegener's continental drift and shows just how similar it was to plate tectonics, making the rejection even more mysterious
- Then, the author introduces the standard explanation (lack of mechanism) but immediately casts doubt on it by showing that other theories have been accepted without full explanations
- Finally, the author presents their own explanation - that the rejection was due to the type of evidence Wegener used (simple field observations) versus the sophisticated instrumental data that supported plate tectonics
Main Point:
Wegener's continental drift theory was rejected not because it lacked a mechanism for how continents moved, but because it relied on simple field observations rather than the kind of high-tech, instrument-based evidence that scientists found more convincing.
3. Question Analysis:
This question asks why the author mentions Hallam's point about ice ages. We need to identify the specific function this citation serves in the author's overall argument structure.
Connecting to Our Passage Analysis:
From our passage analysis, we know that:
- The author first presents the standard explanation for Wegener's rejection (lack of mechanism)
- Then immediately introduces doubt about this explanation through Hallam's counterexample
- Finally presents their own alternative explanation (evidence type)
Specifically, the passage analysis notes that Hallam's point "introduces doubt about the conventional explanation" and "casts doubt on the standard explanation - preparing us for an alternative."
Prethinking:
Hallam's ice ages example serves as a counterargument to the widely accepted view that Wegener's theory was rejected due to lack of mechanism. By showing that other scientific phenomena (ice ages) were accepted without full explanation, Hallam undermines the logic of the standard explanation. This citation functions to weaken the conventional view and set up the author's alternative explanation about evidence types.
Why It's Wrong:
- Hallam's point isn't about current understanding of ice ages, but about historical acceptance
- The focus is on when ice ages were accepted (before full explanation), not on current gaps in knowledge
- This misses the argumentative function of the citation entirely
Common Student Mistakes:
- Focusing on ice ages as the subject rather than as an example?
→ Remember that citations often serve argumentative functions rather than introducing new topics - Missing the temporal aspect ("have been accepted before they could be fully explained")?
→ Pay attention to verb tenses that indicate timing relationships
Why It's Wrong:
- While this captures that Hallam is challenging the geological community's reasoning, it's too general
- The author isn't broadly criticizing inconsistency but specifically addressing one explanation
- This mischaracterizes the author's tone and specific argumentative purpose
Common Student Mistakes:
- Seeing any challenge to scientific reasoning as "criticism for inconsistency"?
→ Distinguish between specific counterarguments and broad criticism - Missing that this is about one specific explanation, not general inconsistency?
→ Track what specific view is being challenged
Why It's Right:
- Hallam's example directly contradicts the "lack of mechanism" explanation
- It shows that scientific acceptance doesn't always require full explanation
- This citation serves to undermine the common view and prepare for the author's alternative
Key Evidence: "However, as Anthony Hallam has pointed out, many scientific phenomena, such as the ice ages, have been accepted before they could be fully explained."
Why It's Wrong:
- Hallam is actually disagreeing with the mechanical basis explanation, not supporting it
- This completely reverses the argumentative function of the citation
- Hallam's position contradicts Gould's reasoning about mechanical explanations
Common Student Mistakes:
- Missing the "However" that signals contrast with the previous explanation?
→ Pay special attention to transition words that indicate argumentative direction - Confusing different experts' positions?
→ Track which expert supports which view throughout the passage
Why It's Wrong:
- Hallam's ice ages example actually undermines Gould's rationale, not supports it
- The "However" introduces contrast with Gould's position
- This completely misreads the argumentative structure
Common Student Mistakes:
- Thinking all expert citations support the same view?
→ Track which experts support which sides of the argument - Missing that Hallam is providing a counterexample to challenge the mechanical explanation?
→ Understand how counterexamples function to weaken arguments