Make a fossil
Overview
Find out how real fossils are formed by fossilising your own toy or object using plaster of Paris or flour.
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What to do
Step 1
Fill your container to about 2cm with sand. If the sand is dry, dampen it with some water. Flatten the surface of your sand with your hands.
Step 2
Push the object you are fossilising as hard as you can into your sand. Make sure you push all of the parts of the object into the surface, especially if it has legs or a tail.
Step 3
Carefully take out your toy or object without moving the sand. You should be left with an impression of the object you are fossilising.
Step 4
Now make up your plaster of Paris or flour solution. WARNING: you need to pour this very quickly or it will set in your jug! Add one cup of warm water and 2 cups of plaster of Paris or flour to your jug. Mix until smooth.
Step 5
Pour the plaster of Paris or flour solution into your fossil impression as quickly but carefully as possible. Make sure you fill up all of the holes with the solution and pour the rest over the top to make a base for your fossil. Leave to set for 48 hours.
Step 6
After 48 hours remove your fossil from the sand and brush off any extra sand with your hand or a paint brush. You should have a fossilised version of your original object.
Things to discuss
Compare your fossil with your original object.
What is the same about them both?
What is different?
What else could you fossilise?
How it works
When a dinosaur (or any living thing) died, the soft parts of it, such as the skin, muscles and internal organs decompose (breakdown or decay) leaving only the hard parts of the body, such as bones, teeth or shell.
If the creatures is near to water, it’s remains are quickly covered with mud, sand and silt. Over thousands, sometimes millions of years, many more layers of sediment build up on top of the remains. The weight and pressure of these layers turn the sediment surrounding the remains into sedimentary rock. You represented this by pushing your object into the sand.
While this is happening, water seeps into the remains and dissolves them, leaving an impression of the remains in the rock. You represented this by removing your object from the sand.
The remains are replaced by minerals in the water leaving a rock replica of the original bones and teeth called a fossil. You represented this by pouring your plaster or Paris or four solution into your fossil impression.
Over millions of years, fossils become exposed at the Earth’s surface and we can find them. This may be because weathering and erosion from wind, rain, ice, heat and rivers break rocks apart and wash the fragments away, exposing fossils. This may also be because of uplift, where the tectonic plates which form the surface of Earth collide and force areas of rock together and upwards. This may also occur where rock are pushed upwards by new igneous rocks forming underneath them.
Did you know?
Fossils of sea creatures have been found at the top of mountain ranges? This is because of uplift!
Other things to try
Visit the Great North Museum: Hancock
Dive into the steamy swamps of a world millions of years older than the one we know today and discover the weird, wonderful and downright terrifying life forms that lived there.
This is one of the museum’s most popular galleries, bringing the past back to life through rare, internationally famous fossils and a huge array of realistic models.
Find our more about the collection, opening times and how to get there.
What you’ll need
- An object to fossilise- it needs to be something hard like a plastic toy or a shell
- 2 cups of plaster of Paris or flour
- 1 cup of warm water
- A jug to mix it in
- A spoon for mixing
- A plastic container bigger than the object you want to fossilise
- Sand- enough to fill your box or bowl to 1 or 2 cm
Duration
20 minutes or so to make. 48 hours to dry.
Suitable for…
Age 4 and up.
Safety notes
You know your children better than anyone, and you should judge whether they’re ready for this activity. You might want to think in particular about:
- Supervision: this activity makes a mess and you may want to watch what children are doing!
- You may want to do this activity outside or to cover surfaces and carpets.
- Supervise children using warm water to avoid scalds and burns.
- The plaster of Paris or flour solution may block sinks and drains. Leave it to set on equipment then scrape it off.
- Follow all safety instruction on plaster of Paris.
- Ensure children don’t put anything in their mouths.
Careers link- Palaeontologist
Palaeontology is the study of ancient life using fossil evidence. This can be remains of prehistoric plants, mammals, fish, insects, fungi and microbes as well as dinosaurs. Things like footprints, burrows, eggs and even poo can be fossilised too.
Fossil evidence shows us how these organisms changed over time and what our planet was like long ago.
Palaeontologists are passionate, open-minded communicators. Could you be a palaeontologist?
