ACT Science: Conflicting Viewpoints Passage (Asteroid Impact vs Deccan Traps Volcanism)

Exact Passage Scenario

• Scientist 1 (Asteroid Impact): 10km bolide at Chicxulub vaporized sulfate rock, causing sudden impact winter (<1 year). Evidence: Global iridium boundary, shocked quartz (>10 GPa).
• Scientist 2 (Deccan Traps Volcanism): Prolonged 500,000-year basalt eruptions released SO2 and CO2, causing multi-stage climate instability. Evidence: Deep mantle plume iridium, pre-boundary species decline.

Question: Which discovery would provide the strongest support for Scientist 1 over Scientist 2?

- A) High SO2 in ancient ocean rocks.

- B) Shocked quartz uniquely dated to a single pulse occurring over less than 1 year at the K-Pg boundary.

- C) Dinosaur decline beginning 200,000 years prior to the boundary.

- D) Iridium-rich layers in volcanic shields.

Solution

Scientist 1 specifies a single, rapid shock event ($<1$ year). Scientist 2 specifies a gradual 500,000-year process. A 1-year pulse of shocked quartz confirms Scientist 1. Correct Answer: B.