How Do Fossils Form?

A fossil is remains or evidence of previous life preserved in the earth's surface. You have probably seen fossils at one time or another. It may have been a fossil of an ancient fern leaf or perhaps some prehistoric creature. It is exciting to look at something that lived millions of years ago. Though scientists have found many, many fossils, they are not all that common. It takes very special conditions for fossils to form. Here's how you can make a modern day fossil.

What Do I Need? 

  • Plaster of Paris
  • Sea shells
  • Leaves
  • Water
  • Cardboard
  • Petroleum Jelly

How Do I Make the Fossil?

Fossils form a number of ways. We will simulate a type of fossil that forms in mud.

Mix a small amount of water with a handful of plaster of paris, the plaster should be smooth and thick.

Spread the plaster of paris onto the cardboard, making it about an inch thick, and just slightly larger than a leaf.


Coat the leaf with petroleum jelly and place it onto the plaster. Press gently down on the leaf to push it into the plaster.

Allow the plaster to dry in a warm place.

Remove the leaf when the plaster is dry and you have a type of fossil! You can try the same thing using sea shells or even models of animals.

How is This Like real Fossils? How else can Fossils form?

      Copyright © 1997 Kathy A. Miles and Charles F. Peters II