Text 1Little is known about how plate tectonics—wherein slabs of Earth's crust move over, under, away from, and against one...
GMAT Craft and Structure : (Structure) Questions
Text 1
Little is known about how plate tectonics—wherein slabs of Earth's crust move over, under, away from, and against one another—began. Some researchers contend that tectonic movements began around 3 billion years ago, often noting that computer models of Earth's mantle temperature at the time indicate that the mantle would have been sufficiently molten to enable the plates to move.
Text 2
Ultimately, any plausible claim about the inception of tectonic movement must rest on empirical evidence from the geological record. Researcher Wriju Chowdhury and his team analyzed the geochemistry of zircon crystals to gain insight into the chemical composition of the magma from which the crystals formed and, based on the data, compellingly argue that plate tectonics may have been occurring as early as 4.2 billion years ago.
Based on the texts, how would the author of Text 2 most likely respond to what 'some researchers contend' as described in Text 1?
By suggesting that the temperature of Earth's mantle 3 billion years ago was likely insufficient to allow for the level of tectonic movement predicted by computer models
By distinguishing between computer models of Earth's mantle temperature that reliably predict the onset of plate tectonics and those that do not
By indicating that computer models of Earth's mantle temperature are still being improved such that new models tend to be much more reliable than their predecessors
By asserting that a more definitive form of evidence than the computer models suggests a different timeline for the onset of plate tectonics on Earth
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| "Little is known about how plate tectonics—wherein slabs of Earth's crust move over, under, away from, and against one another—began." |
|
| "Some researchers contend that tectonic movements began around 3 billion years ago, often noting that computer models of Earth's mantle temperature at the time indicate that the mantle would have been sufficiently molten to enable the plates to move." |
|
| "Ultimately, any plausible claim about the inception of tectonic movement must rest on empirical evidence from the geological record." |
|
| "Researcher Wriju Chowdhury and his team analyzed the geochemistry of zircon crystals to gain insight into the chemical composition of the magma from which the crystals formed and, based on the data, compellingly argue that plate tectonics may have been occurring as early as 4.2 billion years ago." |
|
Provide Passage Architecture & Core Elements
Main Point: Scientists disagree about when plate tectonics began, with some using computer models to suggest 3 billion years ago while others use actual geological evidence to argue for 4.2 billion years ago.
Argument Flow: Text 1 presents the mystery and one computer modeling approach that dates tectonics to 3 billion years ago. Text 2 establishes that valid claims need real geological evidence, then presents research using zircon crystals that pushes the date back to 4.2 billion years ago.
Step 2: Interpret the Question Precisely
What's being asked? How would the Text 2 author respond to the specific claim made by "some researchers" in Text 1?
What type of answer do we need? The Text 2 author's likely reaction or critique of the Text 1 researchers' position
Any limiting keywords? N/A
Step 3: Prethink the Answer
- The Text 2 author establishes that valid claims need "empirical evidence from the geological record" and then presents Chowdhury's research using actual geological evidence (zircon crystals) that suggests 4.2 billion years ago
- The Text 1 researchers rely on computer models and suggest 3 billion years ago
- Key elements the correct answer must have:
- Recognition that Text 2 author prefers empirical geological evidence over computer models
- Acknowledgment that the Text 2 research suggests a different timeline (4.2 vs 3 billion years)
- Understanding that Text 2 sees their evidence as more definitive than computer modeling
By suggesting that the temperature of Earth's mantle 3 billion years ago was likely insufficient to allow for the level of tectonic movement predicted by computer models
- Claims Text 2 author would say mantle temperature was insufficient 3 billion years ago
- Text 2 doesn't critique the temperature models themselves - it critiques relying on models instead of empirical evidence
By distinguishing between computer models of Earth's mantle temperature that reliably predict the onset of plate tectonics and those that do not
- Suggests Text 2 author would distinguish between reliable vs unreliable computer models
- Text 2 author doesn't rank different computer models - they advocate for geological evidence over any computer modeling approach
By indicating that computer models of Earth's mantle temperature are still being improved such that new models tend to be much more reliable than their predecessors
- Implies Text 2 author sees computer models as improving and becoming more reliable
- Text 2 author actually argues we should move away from models toward empirical evidence
By asserting that a more definitive form of evidence than the computer models suggests a different timeline for the onset of plate tectonics on Earth
- Captures that Text 2 author sees geological evidence as "more definitive" than computer models and acknowledges the different timeline (4.2 billion vs 3 billion years ago)