Question 14·Medium·Central Ideas and Details
Geologists examining deep ice cores drilled from Greenland recently uncovered a thick layer of volcanic ash that they dated to roughly 12,000 years ago. Chemical analysis of the ash indicates that it originated from an Icelandic volcano and that the eruption responsible was far larger than any eruption documented in human records. The researchers argue that the ash blanket extended across much of the North Atlantic region and may have contributed to an abrupt climatic cooling at the time.
Based on the text, which choice best describes the Icelandic volcanic eruption?
For detail questions like this, first underline the part of the question that tells you what to look for (here, a description of the eruption). Then quickly reread the sentence or two in the passage that mention that subject and list the key facts in your own words. Check each answer choice against those exact facts: cross out any option that adds new information, contradicts the passage, or changes a key word (like turning “cooling” into “warming”). Usually, one choice will match the passage almost word-for-word—pick that one and move on without overthinking or using outside knowledge.
Hints
Find where the eruption is described
Look back at the sentences that talk about the chemical analysis of the ash and the researchers’ argument. Those lines tell you what the eruption did and what its effects were.
Separate facts from guesses
Ask yourself: which details about the eruption are stated directly in the passage, and which details in the answer choices are not mentioned at all?
Watch for direct contradictions
Check whether any answer choices say the opposite of what the passage says about the eruption’s size or its effect on climate.
Step-by-step Explanation
Clarify what the question is asking
The question asks which choice best describes the Icelandic volcanic eruption based only on information from the passage. So you must restate something the passage clearly says about that eruption—no guesses or outside knowledge.
Locate the key information about the eruption
Focus on the sentences that describe the eruption:
- Scientists found volcanic ash in Greenland.
- Chemical analysis shows it came from an Icelandic volcano.
- The eruption was far larger than any eruption documented in human records.
- Researchers think the ash blanket extended across much of the North Atlantic and may have contributed to an abrupt climatic cooling.
These are the only facts you are allowed to use when judging the answer choices.
Check each answer against the passage details
Now test each option against those facts:
- Choice A talks about the eruption being carefully observed by scientists living at the time. The passage says the eruption was about 12,000 years ago, long before modern science, and never mentions anyone observing it then—only modern geologists studying ice cores.
- Choice B claims it released less material than modern eruptions, but the passage says it was far larger than any eruption documented in human records, which means the opposite.
- Choice D says it caused a prolonged warming period, but the passage says it may have contributed to an abrupt climatic cooling, which directly contradicts that.
Only one answer matches what the passage actually describes.
Identify the matching description
The remaining fact from the passage is that geologists found a thick layer of volcanic ash in Greenland, and chemical analysis showed the ash came from an Icelandic volcano. That means the eruption must have sent ash all the way from Iceland to Greenland, which is exactly what choice C) It dispersed ash that reached Greenland says.