Front

What is the age of rock compared to the ages of other rocks?

Back

Relative age

Front

What is an igneous rock layer formed when lava flows onto Earth's surface and hardens?

Back

Extrusion

Front

What are fossils of widely distributed organisms that lived during a geologically short period?

Back

Index fossil

Front

What is an igneous rock layer formed when magma hardens beneath Earth's surface?

Back

Intrusion

Front

What is the term for the process of wearing away rocks and soil?

Back

Erosion

Front

What do we call the gap in the geological record that represents a period of time where no rocks were formed?

Back

Unconformity

Front

What is the term for the age of a rock in years?

Back

Absolute age

Front

What type of rock is formed from cooled lava?

Back

Igneous rock

Front

What is the process called when sediments are compacted and cemented together?

Back

Lithification

Front

What is the principle that states younger layers of rock are deposited on top of older layers?

Back

Law of Superposition