4-ESS1-1: Reading Rock Layers and Fossils
Also called NGSS 4-ESS1-1 · Topic: Earth's Systems: Processes that Shape the Earth · Earth and Space Science
The Official Wording
Identify evidence from patterns in rock formations and fossils in rock layers to support an explanation for changes in a landscape over time.
Clarification statement: Examples of evidence from patterns could include rock layers with marine shell fossils above rock layers with plant fossils and no shells, indicating a change from land to water over time; and, a canyon with different rock layers in the walls and a river in the bottom, indicating that over time a river cut through the rock.
Assessment boundary: Assessment does not include specific knowledge of the mechanism of rock formation or memorization of specific rock formations and layers. Assessment is limited to relative time.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 4-ESS1-1 Means in Plain English
Fourth graders look for patterns in rock layers and the fossils inside them, then use those clues to explain how a place changed long ago. Seashell fossils in a desert cliff, for example, show that the land was once under water.
Time stays relative: lower layers are usually older than the ones above, with no dates in years. Students do not need to know how each rock forms. This connects to slow and fast Earth events (2-ESS1-1) and to the geologic time scale (MS-ESS1-4).
4-ESS1-1 I Can Statements
- I can explain why lower rock layers are usually older.
- I can use fossils to tell what a place was once like.
- I can describe how a landscape changed using rock layer clues.
4-ESS1-1 Worked Example
A model a class can build in a clear cup, then read like a cliff to tell the story of a place.
What can layers and fossils tell us about how a place changed?
Set It Up: A clear plastic cup, three colors of sand, a few small seashells, and thin clay disks with leaves pressed into them.
- Pour a layer of brown sand and lay a clay disk with leaf prints on top.Bottom: land with plants
- Cover it with a layer of a second sand color.Middle layer seals it in
- Add sand mixed with seashells, then a top layer of the third color.Shells sit above the leaves
- Trade cups with another group and read the layers from bottom to top.Leaves first, shells later
- Write the story: which came first and how the place changed.Land first, then the sea covered it
Reading from the bottom up, the cup showed a place that was dry land with plants and later became covered by the sea.
Why it works: Layers usually pile up with the oldest on the bottom, so the fossils in each layer show what lived there at that time.
Common Mistakes with 4-ESS1-1
Reading layers from the top down
“The top layer is oldest because it's been there longest.”
Try this: New layers settle on top of old ones, like clothes piling in a hamper. Read from the bottom up to go from oldest to newest.
Thinking fossils show the place today
“There are shell fossils, so this desert has sea animals.”
Try this: A fossil shows what lived there when its layer formed. Shells in a desert mean the area was once covered by water.
Guessing exact ages
“This layer is 500 years old.”
Try this: Use words like older and younger. Layers show which came first, not an exact number of years.
Where 4-ESS1-1 Fits
Practice 4-ESS1-1
Quick Check
- In a stack of rock layers, which is usually oldest?
- You find fish fossils in rock on a mountain. What does that suggest?
- A river runs at the bottom of a deep canyon. What could explain the canyon?