Activity: Making your own trace fossils
Strand 4: SA1.1, SA1.3, SA1.4, SA2 and SA3
Date:
Name:
Marks:
/15
INTRODUCTION:
The idea of ‘petrifying fluids’ to explain fossils was developed in the 11 th century by the
Persian physician Avicenna. Petrifying fluids doesn’t mean that the fluids were scared, but is
actually a scientific process where dissolved minerals replace organic matter and basically
turn them into stone. Otherwise known as fossilization.
Fossilization is the process of when living things or traces of living things are turned into
fossils over thousands of years. Fossils are the remains of plants and animals or traces of
their presence, preserved in rocks.
There are two main types of fossils:
1. Petrified/permineralized fossils = hard parts of fossils, such as bones are replaced
with other sedimentary minerals.
2. Trace fossils = most common fossils and occur when impressions or traces of life are
left in the sediment and as the sediment is covered and turned into rock over
thousands of years, so are the impressions.
Fossils are important because they give us an idea of what the Earth was like when the fossil
was living, they teach us about evolution and extinct life forms and they also help us date
rocks.
INSTRUCTIONS:
 In one lesson read through the procedure below and make your own trace fossils.
 While you wait for your fossils to harden, get into groups of 4 and go through the
discussion points below.
 Once you’ve come up with some points within the group, write them down individually
in the spaces below each discussion point.
1
MATERIALS:
Items to create fossils from (leaves, bones,
shells)
Ice cream container/shallow paper cup
Sand
String
Labels
Salt (optional)
Large beaker
Heavy duty bin liner
Stirring stick
Large serving spoon
Plaster of paris
Water to mix the plaster of paris
PROCEDURE:
1. Choose a container (ice cream tub/paper cup) that is appropriate for the size of your
fossil.
2. Label your container with your name.
3. Fill half your container with sand.
4. Make a flattened hollow in the sand and press your fossil into the sand.
5. Line a large beaker with a bin liner or thick plastic bag.
6. The volume of water you need depends on how much plaster of paris you want to make.
7. Pour a volume of water into the lined beaker.
8. Slowly sprinkle in plaster of paris stirring the mixture with a stirring stick continuously
until the mixture begins to thicken.
9. Stop when mixture is the consistency of melted ice cream.
10. Mix in a tablespoon of salt to speed up the drying time.
11. Pour the plaster mix carefully over your fossil and sand using a large serving spoon.
12. While mixture is still wet set a loop of string into the plaster mixture so you can hang
your fossil when it dries.
13. Leave to dry for 1 – 3 hours (next lesson).
14. Clean up putting all disposable items with plaster of paris into bin liner.
Note: plaster of paris mixture will block up drains so don’t dispose of it down any sinks.
15. When plaster has dried, remove the plaster from the sand tray and from the fossil.
16. You have now made you own instant trace fossil to hang up.
2
Group Members:
Discussion Point 1:
(You can click on first line and type in text box)
It is clear to see that fossils are really fragile. Bearing this in mind, why do you think fossils are
so rare? What is needed in order for fossilization to occur? (Some research may be needed to
discuss this)
Discussion Point 2:
The fossils you made were trace fossils. What is the other type of fossil? How do you think
these two fossils differ in terms of their formation process?
3
Discussion Point 3:
How do you think scientists can use deductive reasoning to understand the history of life on
Earth from the fossil record?
4
Discussion Point 4:
South Africa is rich in fossils – The mammal-like reptiles found in the Karoo, Dinosaurs found in
the Drakensberg Mountains, all the hominid fossils from the Cradle of Humankind which is a
World Heritage Site. Discuss how having these fossils impact on South African’s economy?
What does this fossil tourism mean for the people of South Africa?
Mark scheme:
3 = excellent work, no mistakes
2 = good work, 1 – 2 mistakes made
1 = could improve, more than 2 mistakes made
0 = this aspect not done
Item being assessed
Relevant materials were brought.
Procedure was carried out effectively.
Group discussion took place on the 4 points.
Information discussed was written down individually in space provided.
Final trace fossil was produced and checked by teacher.
TOTAL
5
Mark
/3
/3
/3
/3
/3
/15
15 MARKS