Shell fossils found in a layer of sandstone

Fossils and Rock Layers

Grade 4

Paleontologists are scientists who study the history of the world by excavating dirt and rock layers in search of fossils from ancient plants and animals. Sometimes these paleontologists have to wait years for a cliffside to change its formation so that more of a fossil is revealed. We will learn more about this process in this lesson.


Teacher's Guide and Related Standards


I can explain what fossils found in rock layers reveal about the history of the Earth.

Essential Questions

  • How do fossils become exposed in rock layers of cliffs and mountains?
  • What can fossils found in cliffs tell us about the history of Earth?

Maryland Farm & Harvest Clip

Thinking questions:

  • What are the paleontologists hoping to excavate from the cliff layers?
  • What has caused the cliffside to change over time, exposing more fossils within it?
  • What organism(s) do the paleontologists think the fossils in the cliff belong to?


Supplemental Enrichment Activities

Constructing Explanations
and Designing Solutions

Paleontology - The Big Dig

Have students explore the many resources provided to learn about fossils. Allow students to perform a Journal Write and explain what fossils are able to tell us about Earth’s past.

» Go to Website

The History of Planet Earth

The Grand Canyon - The Top Two Rock Layers

By watching the video, students will understand how fossils found in various rock layers tell us the history of that particular location.

Relate this concept to the previous video shown about the paleontologists finding the whale fossils on the side of Calvert Cliffs. Have a discussion about what finding a whale fossil on a landform tells us about what existed there before the land was formed.

» Go to Video


The Oldest Rock Layer

This activity allows students to analyze patterns and to understand that the layers of rock that are deepest in the ground indicate an older time period on Earth. Fossils that are found in the deeper rock layers belong to organisms that lived on Earth long before organisms whose fossils are found in more shallow rock layers.

Have students debate which two organisms (of the four shown) they think have the most similar life cycles.

» Go to Activity

Career Connections


This learning resource is a production of Maryland Public Television/Thinkport.