Chapter 8 Section 1Chapter 8 Section 1Page 190 #’s 1-6Page 190 #’s 1-6

Determining Relative AgeDetermining Relative Age

1. Explain why it is important for 1. Explain why it is important for scientists to be able to scientists to be able to

determine the relative age of determine the relative age of rocks.rocks.

• So they can understand the age and history of Earth

2. State the principle of 2. State the principle of uniformitarianism in your own uniformitarianism in your own

words.words.

• It’s like what happened in the past is just like what is happening now man.

3. Explain how the law of 3. Explain how the law of superposition can be used to superposition can be used to determine the relative age of determine the relative age of

sedimentary rock.sedimentary rock.

• According to the law, a rock layer is always younger than the rock layer below it if the layers are undisturbed.

4. Explain the difference 4. Explain the difference between an unconformity and a between an unconformity and a

nonconformity. .nonconformity. .

• An unconformity is a break in the rock record; a nonconformity is a kind of unconformity in which metamorphic or igneous rock layers are overlain by sedimentary rock layers.

5. Compare an angular 5. Compare an angular unconformity with a unconformity with a

disconformity.disconformity.

• In an angular unconformity, tilted rock layers are overlain by horizontal rock layer. In a disconformity, the rock layers above and below the unconformity are parallel.

6. Describe how the law of 6. Describe how the law of crosscutting relationships helps crosscutting relationships helps scientists determine the relative scientists determine the relative

age of rocks.age of rocks.

• The law of crosscutting relationships helps scientists understand that a body of rock or fault is always younger than any other body of rock that it cuts through.

The End !!!The End !!!