Count from the bottom
The first deposit is the oldest layer in this undisturbed stack.
Fossil Layer Builder
Deposit sediment with selected remains, bury a fossil and compare older layers with younger layers.
Grades 3–5 · Earth Science
Your goal
Build 4 layers. Preserve one leaf fossil in mud in layer 1 counted from the bottom, and bury it under younger layers. Keep other layers fossil-free.
Reduced motion is on. The controls still update the scene.
0 layers built. Target fossil belongs in layer 1 from the bottom. New sediment is younger than the layer it covers.
Layers accumulate from the bottom upward in this undisturbed cross-section. A chosen shell or leaf represents remains that become a fossil if preserved; adding another layer buries it. Sand and mud can contain fossils here, while ash is a fossil-free marker. Real fossilization is uncommon, takes time and can occur in other materials. Folding, overturning and erosion can complicate real rock records. Relative order does not give an exact age.
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Learn with Fossil Layer Builder
Fossil Layer Builder helps elementary students investigate how a layered record forms. Select sand, mud or an ash marker and deposit each new layer on top of the last. Place a chosen shell or leaf in a mud layer, then bury it beneath younger sediment. Goals specify the fossil position counted from the bottom and the total number of layers. Students can erode the top layer to revise a stack and observe why removing younger material can expose older remains without changing their original order.
What to look for
Bury the remains
Choose mud and the requested fossil, deposit that layer, then add fossil-free sediment above it.
Use erosion carefully
Erosion removes the top layer first. It can expose a fossil that was buried.
For teachers and curious learners
Use an undisturbed sediment stack to connect burial, erosion and relative layer age. Ask students to predict what will happen, change one setting, and explain what they observe. Learn gives a starting point. Practice and Challenge offer new goals with the same scene.
An undisturbed stack deposits upward and erodes only from the top. Sand and mud may contain selected fossils; ash is a fossil-free marker here. Real preservation is uncommon; fossilization time, folding and overturning are omitted.