Understanding and Making Fossils

Brachiopod fossils
Brachiopod Fossils

NPS Photo


Students will:

  • · define what a fossil is.
  • · identify what the environment that created the limestone was and list two types of fossils found in the limestone.
  • · explore how fossils are created by making their own.


  • · 2 cups flour
  • · 1 cup salt
  • · 1 tablespoon vegetable oil
  • · 1 teaspoon alum
  • · ½ - 1 cup water
  • · 4" X 4" square of wax paper for each student
  • · Leaf, shell, or other material from which to make an imprint
  • · Paint and paint brush

Background information:

Fossils are the preserved remains or traces of plants, animals, and other organisms preserved in rocks. Because fossils provide evidence of past life geologists and paleontologists use them to help us understand the history of the earth.

Fossils are found in sedimentary rocks. These rocks form from deposits that accumulate on the Earth's surface such as lake or river bottoms, sandbars, beaches, and oceans.

In order for a plant or animal to become fossilized it must contain hard parts such as bones, teeth, cartilage, or shells and it must be buried quickly and protected from scavengers. Other evidence of life such as tracks or imprints can also become a fossil. These are called trace fossils.

The limestone that Wind Cave is in began as sediments in a shallow tropical sea during the Mississippian time period. Today, fossils of marine shell life are found in the cave. Brachiopods, (clams), and gastropods (snails), are found in this limestone.


Create a fossil. Mix the ingredients for the fossil dough creating enough dough for each student to make a one-inch ball


2 cups flour

1 cup salt

1 tablespoon vegetable oil

1 teaspoon alum

½ - 1 cup water

Directions for making dough:

1. Combine first four ingredients. Add a small amount of water at a time until the mixture is the consistency of bread dough. Knead until smooth.

2. Shape into balls one-inch in diameter, one for each student.

3. Store in an airtight container or plastic bag until needed. For long-term storage, keep in the refrigerator


1. Provide each student with a square of wax paper.

2. Provide each student with enough dough to make a one-inch ball.

3. On the wax paper, press the dough ball into a disc. The disk should be about the size of a half-dollar.

4. Have each student select a piece of material (shell, bone, leaf, etc.) from which to make an imprint.

5. Press the selected material into the dough. Remove the material, leaving an imprint. Set aside to dry.

6. When dry, may be painted.

Another fun activity is to use cookie dough instead of the above recipe and then bake the cookies and then the students can eat their fossils!

The following websites have additional instructions on fossils.

http://www.michigan.gov/documents/deq/p06create_304664_7.pdf Provides information about fossils and makes them with a flour type dough.

http://www.teachervision.fen.com/science/lesson-plan/5274.html creates fossils using plaster of Paris.

Last updated: April 10, 2015

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