Welcome to Science 1/10• As you enter put your initials on the timeline in the

order that you arrive in the room. Have your HW out.

• Who was the first person in the room? Last?• How does the timeline show this?• The first people in the room put their initials at the

beginning of the timeline. As people came into the room later, they put their initials at the end of the timeline.

Relative Dating• We determine the age of a fossil or rock by

looking at its relative position in layers of rock. Ages of Rock Layers

Superposition• Principle that states younger rocks lie

above older rocks in undisturbed sequences.

• “Younger Over Older”

Do rock layers always stay in order?

• Absolutely Not!!!

• Disturbances- Forces that disrupt the sequence of rock layers.

• Disturbances make it difficult for scientists to determine the ages of rocks.

Rock Layers

Gaps in the Record

• Unconformity- a layer of rock that is missing from part of the geologic column

• Why are unconformities important?

• Scientists must question whether the missing layers were actually present or if they were somehow removed.

• animation

Unconformity

Rock Layers Lab• 1. Partner Lab

• 2. Work together and work quietly

• 3. Objective: To use fossils and geologic features to determine the relative ages of rock layers.

• 4. Lab will be evaluated for accuracy. If you have a question please ask.