Law of Superposition/Index Fossils

Front

What is the Law of Superposition?

Back

The Law of Superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest layers are at the top.

Front

What is an index fossil?

Back

An index fossil is a fossil that is used to define and identify a particular time period in the geological time scale. It must be widespread, abundant, and short-lived.

Front

Why is fossil #4 not a good index fossil?

Back

It is not short-lived (in numerous layers).

Front

According to the Law of Superposition, which layer is the youngest?

Back

The youngest layer is the one at the top.

Front

Where are the oldest fossils typically found according to the Law of Superposition?

Back

Oldest fossils are found near the bottom of the rock layers.

Front

What does it mean if a fossil is widespread?

Back

A widespread fossil is found in many different geographic locations, indicating it lived during a specific time period.

Front

What characteristic makes a fossil a good index fossil?

Back

A good index fossil is one that is abundant, widespread, and existed for a short period of geological time.

Front

In a rock layer diagram, how can you identify the oldest layer?

Back

The oldest layer is typically the one at the bottom of the diagram.

Front

What type of animal is considered the youngest in a fossil site?

Back

The youngest animal is the one that appears in the most recent layers of rock.

Front

What is the significance of index fossils in geology?

Back

Index fossils help geologists date rock layers and correlate them across different locations.