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Difficulty: Very hardInferences and Implicit Meaning

In his 1885 treatise *Das Antlitz der Erde*, geologist Eduard Suess posited the former existence of Gondwanaland—a vast supercontinent uniting South America, Africa, India, and Australia—to account for the striking late-Paleozoic distribution of *Glossopteris* seed ferns across these disjunct landmasses. Suess's synthesis, however, was fundamentally constrained by his adherence to contractionist geophysics, which viewed oceanic basins not as permanent features modified by lateral drift, but as sunken continental segments that collapsed following planetary cooling. Consequently, to explain why identical *Glossopteris* assemblages appeared across vast oceanic divides without invoking transoceanic seed dispersion—given that *Glossopteris* seeds were heavy and non-buoyant—Suess proposed transoceanic land bridges that subsequently subsided into the mantle. While contemporary paleobotanists praised Suess for cataloging floristic congruences, his model created an unacknowledged paradox for physical oceanography: the thermal subsidence of land bridges required crustal densities incompatible with emerging gravimetric measurements of the oceanic floor. Thus, early twentieth-century critics did not challenge Suess's empirical botanical mapping, but rather the geophysical mechanism he invented to preserve static continental positions.

Based on the passage, which of the following can be inferred regarding early twentieth-century critics of Suess's Gondwanaland hypothesis?

  1. Their skepticism was primarily prompted by physical measurements of crustal density rather than by flaws in Suess's paleobotanical documentation.Answer
  2. B
    They rejected the premise that Glossopteris seeds lacked the structural adaptations necessary for long-distance marine dispersal.
  3. C
    They successfully proved that oceanic basins were permanent structural features that could never undergo vertical subsidence.
  4. D
    They contended that Glossopteris flora originated exclusively in South America before migrating across temporary land bridges.
  5. E
    They dismissed Suess's empirical cataloging of floristic similarities as methodologically flawed and insufficient to demonstrate continental continuity.

Answer

The critics' skepticism was primarily prompted by physical measurements of crustal density rather than by flaws in Suess's paleobotanical documentation.
The passage explicitly notes that the subsidence of land bridges required crustal densities that were incompatible with emerging gravimetric measurements of the ocean floor, and concludes that early twentieth-century critics challenged this geophysical mechanism rather than Suess's botanical mapping. Therefore, it is directly supported that their skepticism was prompted by physical measurements of crustal density rather than botanical errors.

Step-by-Step Solution

1
Analyze the question stem to identify the target of inference.
The target is what can be inferred about early twentieth-century critics of Suess's Gondwanaland hypothesis.
The stem explicitly asks for a valid inference regarding these critics based on passage evidence.
2
Locate relevant passage statements regarding the critics and Suess's model.
The text states that Suess's land bridge subsidence required crustal densities incompatible with gravimetric measurements, and that early 20th-century critics challenged the geophysical mechanism rather than the empirical botanical mapping.
Synthesizing these two statements establishes why the critics objected.
3
Match the synthesized evidence to the option choices.
The option asserting that skepticism stemmed from physical measurements of crustal density rather than botanical mapping errors directly captures this implicit relationship.
It restates the logical core of the final two sentences without introducing outside facts or scope shifts.

Key Concept

Drawing implicit conclusions from juxtaposed claims in dense academic prose
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Topics

Inferences and Implicit Meaning

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