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Difficulty: EasyIdentifying Points of Disagreement

Two scientists discuss the cause of the Cretaceous-Paleogene (K-Pg) mass extinction 66 million years ago.

Scientist 1
The K-Pg extinction was caused by a large asteroid impact. This impact released a massive dust cloud that blocked sunlight, causing rapid global cooling and halting photosynthesis. The global iridium layer found at the K-Pg boundary is evidence of this asteroid, as asteroids are rich in iridium.

Scientist 2
The K-Pg extinction was caused by massive volcanic eruptions of the Deccan Traps. These eruptions released volcanic dust and sulfur dioxide that blocked sunlight, leading to global cooling. The iridium layer at the K-Pg boundary was deposited by volcanoes, as iridium is brought up from Earth's deep mantle during major eruptions.

Match each scientific statement with the corresponding viewpoint or hypothesis description.

  • An asteroid impact was the primary trigger of the K-Pg mass extinction.Supported only by Scientist 1's impact hypothesis.
  • Volcanic eruptions of the Deccan Traps were the primary trigger of the K-Pg mass extinction.Supported only by Scientist 2's volcanic hypothesis.
  • The K-Pg boundary iridium layer originated from an extraterrestrial source.Attributed to an asteroid by Scientist 1.
  • The K-Pg boundary iridium layer originated from Earth's interior.Attributed to Earth's mantle by Scientist 2.

Answer

The statement attributing the extinction to an asteroid impact matches Scientist 1's impact hypothesis; the statement attributing the extinction to Deccan Traps volcanism matches Scientist 2's volcanic hypothesis; the statement attributing the iridium layer to an extraterrestrial source matches Scientist 1's explanation; and the statement attributing the iridium layer to Earth's interior matches Scientist 2's explanation.
Scientist 1 proposes an asteroid impact as the extinction trigger and the source of boundary iridium, while Scientist 2 proposes volcanic eruptions (Deccan Traps) as the trigger and Earth's deep mantle as the source of boundary iridium.

Step-by-Step Solution

1
Analyze Scientist 1's viewpoint regarding the cause of the extinction and the source of the boundary iridium.
Scientist 1 claims the extinction was caused by an asteroid impact and the boundary iridium layer came from the iridium-rich asteroid.
To identify the claims supporting Scientist 1's hypothesis.
2
Analyze Scientist 2's viewpoint regarding the cause of the extinction and the source of the boundary iridium.
Scientist 2 claims the extinction was caused by volcanic eruptions of the Deccan Traps and the boundary iridium layer came from Earth's deep mantle.
To identify the claims supporting Scientist 2's hypothesis.
3
Match the statements on the left to the corresponding descriptions on the right using these points of disagreement.
The asteroid trigger matches Scientist 1's trigger, the volcanic trigger matches Scientist 2's trigger, the extraterrestrial iridium matches Scientist 1's explanation, and the mantle iridium matches Scientist 2's explanation.
To complete the matching task by pairing the disagreeing statements with their correct proponents.

Key Concept

Identifying points of disagreement between conflicting scientific hypotheses regarding the primary cause of an event and the origin of geological evidence.
Estimated Time:45s
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Topics

Identifying Points of Disagreement

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