Gummy Bread Fossils
Subject Area: Earth Sciences/Science
Grade Level: 3rd – 8th grade
Prerequisite Knowledge: The understanding that living beings are made out of carbon
Goal: To provide a believable and visual representation of how heat and pressure can modify
the structure of organic matter
Time Required: 2 days (second day 2 days after first)
Opening: Did you know that coal, crude oil (from which gasoline and diesel and even petroleum
jelly are made) and natural gas are all fossil fuels?
Can you think of some ways in which we use fossil fuels today? Let’s try to name a few of them
together.
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Fossils are old right? Fossil fuels are even older than the fossils you have perhaps seen in
museums. Watch the video to see how fossil fuels were formed.
Fossil Fuel Formation Video
Do you remember how many years ago the prehistoric animals and plants that make up the
crude oil we use today lived on Earth?
It’s hard to believe that just sand and mud and water and the pressure from the weight of these
can turn plants and animals into oil and gas, isn’t it? But they can…only we’re missing one key
ingredient – TIME.
Layers of sand and mud and water over lots and lots of time – like more than two hundred
million years – is what it takes to turn dead plants and animals into fossil fuels. 100-200 million
years ago is a very, very long time ago. Tyrannosaurus Rex
lived and killed smaller dinosaurs on Earth just 65-70
million years ago. So most of the fossil fuels we use today
are much older than that.
I’d like to show you how to make fossil fuels, but we don’t
really have 200 million years to spare. Luckily, we can do
what is called a simulation. We can use other stuff to stand
in for the plants and animals and microorgansims at the
bottom of the ocean and for the layers of sand and mud that got dumped on top. It’s take us a
few days, however, but not nearly as long as it would take to get natural gas.
We’re going to use gummy candy as our plants and animals and different coloured bread to be
our different layers of mud and soil and sand. Take a look at the picture to get an idea of what
the whole thing will look like.
Here’s what we’re going to do:
1. The bottom of the ocean is white, so let’s put a slice of white bread on top on one side
of the paper towel. Great, now we have our ocean floor.
Remember we are going to fold the paper towel over the last piece of bread in the end.
2. Place one gummy fish on top of your ocean floor (white bread slice).
3. Now place the slice of rye bread on top. Your slices of bread should be lined up with
each other and your gummy fish should be hidden from sight. The rye bread stands in
for the sediments deposited by the ocean. Remember that this actually takes a very long
time to happen.
4. Now scatter your remaining gummy fish over the rye bread followed by the final slice of
bread. This represents the natural processes that have taken place over millions of
years, as more sand and sediments have been deposited by wind and ocean currents.
5. Now fold the paper towel over the entire thing to cover your bread fossil.
Are we done? Not quite. What is missing to fossilize your fish? Can you guess?
6. PRESSURE. We need to add pressure. To do that, place 1-2 heavy textbooks or
dictionaries on top to simulate the natural process of pressure from sediment deposits
and the weight of the ocean.
7. Leave your model for 2 days. Each day represents 100 million years of natural time.
8. After one or two days, observe the bread fossil. Push a clear straw straight down into
the bread and “extract” a core sample. Observe the layers through the straw.
9. Try to separate the layers of bread. Why do you think the layers are difficult to
separate? Now try to extract the gummy fish. Can you identify the fish’s impression in
the bread (fossil)? How about the bread around the fossil? What do you think that will
look like after the fossil has completely melted?
The residue left by the gummy fish on the bread layer just above it after the gummy fish has
completely melted represents oil deposits left by the dead ocean plants and animals. Over
millions of years the pressure from the deposits and water liquefies the remains and turns it
into fossil fuels.
Post-Activity Questions:
1. So, fossil fuels contain very high amounts of carbon that have been compacted and
liquefied by time and pressure. What is released into the atmosphere when fossil fuels
are burned?
2. What do you think fossil fuels have to do with global warming and climate change?