Dating Rock Layers & Fossils

Front

What is the Principle of Superposition?

Back

In an undisturbed sequence of rock layers, the oldest layer is at the bottom and the youngest layer is at the top.

Front

What is absolute age?

Back

The numerical age, in years, of any object.

Front

What does the Principle of Cross-Cutting Relationships state?

Back

An igneous intrusion is always younger than the layers it cuts across.

Front

What are inclusions in geology?

Back

Older rocks contained within newer rocks.

Front

What is relative age?

Back

The age of an object in comparison to another object, without providing a specific numerical age.

Front

What is the significance of fossils in rock layers?

Back

Fossils help to determine the relative ages of the rock layers in which they are found.

Front

What is an igneous intrusion?

Back

A body of igneous rock that has formed from molten rock that has cooled and solidified.

Front

What are unconformities?

Back

Gaps in the geological record that indicate periods of erosion or non-deposition.

Front

What is the Law of Original Horizontality?

Back

Layers of sediment are originally deposited horizontally under the action of gravity.

Front

What is a fault in geology?

Back

A fracture or zone of fractures between two blocks of rock.