4. Dating the Earth

Igneous rocks

Metamorphic rocks

Sedimentary rocks

Lava flows

Gives the exact numerical age of a rock or fossil

Determines the order of events without exact dates 

Uses isotopes to date fossils

Tells the age of Earth in billions of years

Older layers are found above younger ones

All layers are the same age

Younger layers are found above older ones

The age of the rock can be determined using carbon-14

Superposition

Cross-cutting

Faunal succession

Original horizontality

Younger than the rock layers it cuts through

Older than the rock layers

The same age as the surrounding layers

Made of igneous rock

A, B, C, D, E, F, G, H, I, J, K, L, M, N

E, G, L, C, H, M, D, I, A, N, K, B, F

F, B, K, N, I, A, D, M, H, C, L, G, E

H, E, G, L, A, C, M, D, N, B, K, F, I

The time it takes for a fossil to form

The age of the Earth

The time it takes for half of a radioactive substance to decay

The process of layering sediments

Uranium-238

Potassium-40

Carbon-14

Lead-206

Cross-cutting relationships

Radiometric dating

Law of faunal succession

Principle of original horizontality

The exact position of fossils

The precise age in years

The sequence of rock layers

The cause of rock formation