Fascinating Fossils
Coal seams like the one at Bengalla often contain fossils of the organisms that once lived there. In this activity you will make your own fossils.
Purpose: To determine how fossils are preserved.
| What You Need:
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What To Do:
1. Place a piece of clay on the plastic plate.
2. Rub the outside of the sea shell with a little bit of vaseline.
3. Press the sea shell into the clay.
4.
Carefully remove the sea shell so that a clear imprint of the shell
remains in the clay (if it doesn’t work, smooth the clay and try again).
5.
Mix 4 spoons of plaster of paris with 4 spoons of water in the plastic
cup. Stir the mixture until it looks like thick cream. (Carefully add a
little more water if it is too dry).
6. Fill the imprint in the clay with plaster mixture.
7. Carefully use a toothpick to write your initials on the modelling clay.
8. Leave the plaster to harden (it will take about 15 to 20 minutes).
9. Clean up the mess while you are waiting!
- Rinse the plastic cup and spoon in water in the Rinse Bucket. Then leave them to soak in the Soak Bucket. (Buckets are behind you on the floor).
- Wipe the vaseline off the shell with paper towel.
- Wipe down the bench.
10. When the plaster is hard, carefully separate the clay from the plaster mould.
Challenge:
The modelling clay and the plaster are both examples of fossils. The clay represents the soft mud of ancient times. Living organisms made imprints in the mud. If nothing collected prints, the mud dried, forming what is now called a CAST FOSSIL. When sand or other sediments filled the imprint, a sedimentary rock formed with the print of the organism on the outside. This type of fossil is called MOULD FOSSIL.
- Look at the picture below. The different parts of your model have been labelled.
- Can you match these labels with the list on the right by drawing a line to join them?
 | Plaster shape | Cat fossil |
| Plaster | Sedimentary rock | |
| Imprint | Soft mud | |
| Modelling clay | Mould fossil |
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