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Difficulty: EasyInferences from the Text

Lichenometry is a dating technique based on the predictable, radially symmetrical growth rates of crustose lichen species, such as Rhizocarpon geographicum, colonizing freshly exposed rock surfaces. Because these organisms require direct exposure to sunlight and atmospheric moisture while remaining intolerant of rapid substrate erosion, successful colonization occurs almost exclusively on stable rock faces immediately following glacial retreat or landslide events. However, because lichen growth rates vary inversely with altitude and depend heavily on microclimatic humidity, researchers cannot establish universal growth curves; instead, calibration curves must be constructed independently for each specific geographic microregion using substrates of historically documented ages.

Which of the following can be most reasonably inferred from the passage regarding the application of lichenometry?

  1. A
    Crustose lichens colonize rapidly eroding rock surfaces more effectively than stable substrates due to higher nutrient availability.
  2. B
    A single universal growth curve can accurately determine the exposure age of rock surfaces across varying elevations worldwide.
  3. Accurately dating rock surfaces in a particular valley requires comparing lichen measurements against baseline growth data calibrated specifically for that local environment.Answer
  4. D
    Lichenometry can be reliably performed only on rock formations that are completely sheltered from sunlight and precipitation.
  5. E
    Crustose lichens were historically cultivated by human populations to stabilize unstable moraines after glacial retreat.

Answer

Accurately dating rock surfaces in a particular valley requires comparing lichen measurements against baseline growth data calibrated specifically for that local environment.
The correct statement is logically entailed by the passage's concluding sentence, which notes that variations in altitude and humidity prevent universal growth curves and require independent calibration curves for each specific geographic microregion.

Step-by-Step Solution

1
Identify the key claims in the passage regarding the constraints and requirements of lichenometry calibration.
The passage states that growth rates vary with altitude and humidity, preventing universal curves and necessitating independent calibration curves for each microregion.
Inference questions require finding the choice that is directly supported by the combination of stated facts without extrapolating beyond the text.
2
Evaluate the answer choices against the textual evidence.
The statement that local baseline data tailored to the specific environment is necessary for accurate dating directly restates the requirement for microregion-specific calibration curves.
A valid inference must follow necessarily or with strong logical support from the passage statements.

Key Concept

Drawing necessary textual inferences from explicit qualifying conditions in scientific exposition.
Estimated Time:1m 0s
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Inferences from the Text

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