Elevated Levels of Iridium Are Found in the Geologic Layer

question 20

Multiple Choice

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

• A)Yes. Iridium is a common metal on Earth but rarely accumulates in a singe 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.

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Definitions:

Visuospatial Sketchpad

A component of working memory responsible for temporarily holding and processing visual and spatial information.

Episodic Buffer

The system that binds visual and verbal information in the long-term store and retrieves information from the long-term store.

Central Executive

The part of the brain's working memory system responsible for overseeing and regulating the flow of information from and to its various components.

Episodic Buffer

A component of the working memory system that integrates information from different sources into a single, multi-dimensional representation.