Explore 1 The Law of Superposition

Refer to the diagram below that illustrates sedimentary rock layers. Which of the following statements best describes the law of superposition?

• The youngest rock layers are found at the bottom of the diagram.
• The oldest rock layers are found at the top of the diagram.
• The youngest rock layers are found at the top of the diagram.
• All rock layers are the same age.

What do scientists use the law of superposition for?

• To determine what type of fossil they have found
• To determine the age of the fossil
• To find new fossils hidden in rock layers

Scientists working in the desert discover the fossil of a marine (water) animal. What conclusion might they draw?

• This area was once underwater
• This animal must've come on land before it died
• Someone must've moved this fossil from its original location

What is the Law of Superposition?

• Rock layers on top are younger than layers on bottom
• Rock layers on bottom are younger than layers on top
• All rock layers are the same age
• Rock layers form randomly with no order

If you find a fossil in the bottom layer of rock, what can you conclude?

• It's the newest fossil
• It's from last year
• It's the oldest fossil
• You can't determine its age

Which example best shows the Law of Superposition?

• A sandwich where all ingredients were mixed together
• A layer cake with the oldest layer on top
• A stack of newspapers with today's paper on top
• A pile of rocks arranged by size
• Option 5

What might disturb the normal order of rock layers?

• Wind erosion
• Earthquakes and folding
• Rain and snow
• Plant growth

Which statement about rock layers is FALSE?

• New layers form on top of old ones
• Bottom layers are usually the oldest
• Middle layers are always empty
• Layers can contain fossils

What type of rocks does the Law of Superposition work best with?

• Metamorphic rocks
• Sedimentary rocks
• Igneous rocks
• All types equally

What can be found between rock layers that helps scientists study them?

• Modern garbage
• Living animals
• Fossils and minerals
• Growing plants