Elevated Levels of Iridium Are Found in the Geologic Layer

question 2

Multiple Choice

Elevated levels of iridium are found in the geologic layer at the K-Pg boundary. Is this unusual?

• A) Yes. Iridium is a common metal on Earth but rarely accumulates in a single layer.
• B) No. Iridium is a rare element on Earth, but geological layers of iridium are not uncommon.
• C) Yes. Iridium is a rare metal on Earth.
• D) Yes. Composition differences between geological layers tend to equilibrate over time.