Absolute/Relative Dating 22

Front

What law states that any geologic feature that cuts across other layers is younger than the layers it cuts across?

Back

Law of crosscutting.

Front

Why are trilobites considered good index fossils?

Back

They are abundant, widespread geographically, and only lived for a short time.

Front

What is absolute age?

Back

The age of rock determined by radiometric dating.

Front

What is the term for the amount of time it takes for 50% of the remaining radioactive material to decay into stable material?

Back

Half-life.

Front

According to the law of __________, in horizontal sedimentary rock layers, the oldest layer is at the bottom and the youngest layer is at the top.

Back

Superposition.

Front

What is relative dating?

Back

Determining the age of rocks or fossils in relation to other rocks or fossils.

Front

What is the principle of original horizontality?

Back

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

Front

What are index fossils?

Back

Fossils of organisms that were widespread but only lived for a short period of geologic time.

Front

What is the significance of the half-life in radiometric dating?

Back

It helps determine the age of rocks by measuring the decay of radioactive isotopes.

Front

What does the law of superposition state?

Back

In undisturbed sedimentary rock layers, the oldest layers are at the bottom.