The Earth's History — Test

Question 3 • Earth and Space Science

How does the iridium layer help geologists correlate rock layers across different locations?

Answer

Because of its unique properties, it is a key bed that can be easily identified in many locations worldwide.

The presence of this layer proves that all living organisms died during the impact, and new types of organisms appeared in their place.

It can be used as a key bed because it is very thick and is surrounded by the same rock type in all locations.

It is the only layer that contains fossils of both dinosaurs and mammals in all of these locations.

Explanation

The iridium-rich layer is unusual and recognizable in rocks around the world, so geologists can use it to match rock layers from different locations. A distinctive layer used for correlation is called a key bed. Choice A is wrong because the layer’s usefulness does not depend on being very thick or surrounded by the same rock type.

AI-written and checked against the verified answer.

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