6A Relative Age of Rocks

Front

What is an unconformity?

Back

A gap in the geologic record that shows where rock layers have been lost due to erosion.

Front

What is relative age?

Back

The age of rock compared to the ages of other rocks.

Front

What was the name of the supercontinent that existed 250 million years ago?

Back

Pangaea.

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What is absolute age?

Back

The age of rock given the number of years since the rock formed.

Front

What is an index fossil?

Back

Fossils of widely distributed organisms that lived during a geologically short period.

Front

What does the term 'geologic record' refer to?

Back

The history of Earth as recorded in the layers of rock.

Front

What is erosion?

Back

The process by which rock and soil are worn away and removed from their original location.

Front

What is a fossil?

Back

The preserved remains or traces of ancient organisms.

Front

What is the principle of superposition?

Back

In undisturbed rock layers, the oldest rocks are at the bottom and the youngest are at the top.

Front

What is a rock layer?

Back

A single layer of rock that is part of the Earth's crust.