Question

Iridium is a component of cosmic dust that rains down upon the earth at a constant rate. Why did Luis Alvarez suggest measuring iridium levels in the K-T boundary?

A. He hypothesized that the layer was caused by a supernova explosion.
B. He was looking for a way to determine how quickly the layer had been deposited.
C. He hypothesized that the layer was caused by an asteroid impact.

Answer 1

B. He was looking for a way to determine how quickly the layer had been deposited.

Alvarez thought that if the layer formed over thousands of years, he might be able to detect iridium. Instead, iridium levels were 30 times greater than the surrounding rock, prompting researchers to investigate alternate iridium sources.