What are some Patterns Fossils Show Us? (Unit 7: Lesson 3)

Which fossil’s relative age cannot be determined based on its position?

• a fossil found in every rock layer

• a fossil found in the top rock layer

• a fossil found in a middle rock layer

• a fossil found in the bottom rock layer

Which sentence describes a reason it can be difficult to determine the relative age of rock layers?

• The rock layers can contain fossils.

• New rock layers form on top of old ones.

• Erosion can wear away some or all of a rock layer.

• People drill into mountains exposing the rock layers.

How could relative age be demonstrated using a stack of newspapers?

• by noting the dates of the top and bottom papers

• by describing the placement of the papers within the entire stack

• by comparing the stack of papers to a stack from a different newspaper

• by identifying the age of each paper by the date listed at the top of each one

What does the fossil record refer to?

• all fossils in the rock layers on Earth

• an encyclopedia of fossil photos

• the fossils in a layer being studied

• a recording of fossil names

Scientists use fossils to describe how all of the environments on Earth have changed over time. Which fossil discovery represents a change in the environment where the fossil was found?

• polar bear bones in Alaska

• seashells in the sand at the beach

• Fish in rocks on top of a mountain

• horse bones in soil in the prairie

Explain why having more than one type of fossil in each rock layer would be helpful when determining relative age.

A class took a field trip to the seashore to study this rock sequence. It is full of fossils such as sea stars that lived in the ocean, Triceratops that lived on land, Plesiosaurs that lived in the ocean, and snails that lived on land.

Use these fossils to explain the changes to the environment that occurred while these rock layers were being formed.