RELATIVE DATING

Front

What is relative dating?

Back

Relative dating is a method used to determine the age of rocks and fossils in relation to one another, without determining their exact age.

Front

What does the law of superposition state?

Back

In an undisturbed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest layers are at the top.

Front

What is the law of crosscutting relationships?

Back

The law of crosscutting states that a geological feature (like a fault or intrusion) that cuts through another is younger than the feature it cuts.

Front

What are index fossils?

Back

Index fossils are fossils of organisms that were widespread but only existed for a short period of time, used to date the layers of rock.

Front

What are the two main traits of good index fossils?

Back

Good index fossils are widespread geographically and have a short lifespan.

Front

Where is the youngest material of the ocean floor found?

Back

The youngest material of the ocean floor is found at mid-ocean ridges.

Front

What is an intrusion in geology?

Back

An intrusion is a body of igneous rock that forms when magma pushes into existing rock layers and solidifies.

Front

How do sedimentary rocks usually form?

Back

Sedimentary rocks usually form horizontally as sediments accumulate in layers over time.

Front

What is an unconformity?

Back

An unconformity is a gap in the geological record that occurs when rock layers are eroded or when sediment is not deposited for a period of time.

Front

What is the significance of fossils in relative dating?

Back

Fossils help to establish the relative ages of rock layers and can indicate the environment in which the rocks were formed.