STRATA EXPERIMENT (Part 1)
OBJECTIVES
The students will prepare different layers of deposition with fossils inside
MATERIALS
clean Plaster of Paris
one empty milk carton or milk jug for each student
one paper plate with rim or Styrofoam cup per student
cooking oil
fake fossils (ex: boiled chicken or turkey bones, plastic fish, plant leaves with stems)
TEACHER PREP
1. Photocopy one Activity Sheet per student.
2. Pre-mix the Plaster of Paris. Create four different colours by adding food colouring
and mixing in separate bowls.
ANTICIPATORY SET
1. Explain to the students that we are going to create our own section of the earth. The
earth has layers which have different rock and mineral compositions, textures and
colours. To simulate this we will use food colouring in plaster of paris. Just as real
fossils are buried in the earth, we will bury fossils of our own.
PROCEDURE
1. Explain to the students that the bottom of the container holds the oldest fossils. As we
go up the container, the fossils get newer and newer. The students will need to determine
the relative ages of their fossils and organize them from oldest to newest. Students then
draw a plan of how their project is going to look. They depict each layer's colour and
contents on the Student Sheet.
2. Pour a bit of one colour of Plaster of Paris into the milk carton or milk jug. Coat a
fake fossil with oil. Tell the students that this is your oldest fossil and goes in first in the
very bottom layer. Put the fossil in and cover with a thin amount of the same colour of
Plaster of Paris.
3. Explain that the next layer is going to be a different colour so that we can tell the
layers apart and find the fossils later. Pick up the next fossil item and coat it with oil. Put
a bit of another colour of Plaster of Paris into the container and then drop the fossil in.
Place more Plaster of Paris of the same colour on top to burry the fossil.
4. Continue placing one fossil in each different coloured layer. Stop when you run out of
room and the container is full.
5. Leave the containers in a safe place to harden.
CLOSURE
1. Ask the students to clean up and complete part one of the
Activity Sheet.
STRATA EXPERIMENT (Part 2)
OBJECTIVES
The students will examine different layers of deposition and fossil layering. They will
identify the principles of stratigraphy.
MATERIALS
containers of Plaster of Paris and fake fossils from Part 1 of Strata
fake fossils (ex: boiled chicken or turkey bones, plastic fish, plant leaves with stems)
dental picks, clean and dry paint brushes, large nails and flathead screwdrivers for each
student
TEACHER PREP
1. Gather necessary materials and set up.
ANTICIPATORY SET
1. Explain the principles of stratigraphy. Pass out the Student Sheet. Students must first
complete Strata Part 2A before they are allowed to pry apart and examine the fossils and
impressions.
PROCEDURE
1. Explain to the students that today we will excavate our fossils. Explain how to cut/tear
away the milk carton or milk jug while leaving the layers intact. Examine the varying
thickness of the layers. Ask the students how layers might vary in real life. What might
cause a layer to be thick? thin? What might cause layers to be uneven?
3. Show the students how to pry apart the layers. Pry one apart and examine how the
impression is similar to the fossil. Explain to the students that separating the first layer is
the practice layer. After separating their second layer they are to draw a picture of the
fossil and the impression on their Strata Part 2B sheets and complete the sheets.
CLOSURE
Allow the students time to separate the remaining layers and examine their fossils and
impressions. Ensure that they complete the sheet first.
.
Name: _________________
STRATA (Part 2A)
LAWS OF STRATIGRAPHY:
1. Superposition - In a normal sequence of sediments, the youngest
layers are on the top.
2. Original horizontality - The way sedimentary or volcanic rocks are
deposited is such that the upper surface remains horizontal.
3. Fossil succession - Groups of plants and animals live at specific times
and are found in specific layers. This creates a specific order over time.
4. Unconformities - Sometimes older layers partly erode or are uplifted
before new layers can be made on top. This can cause irregularities in
the geologic time sequence. Entire layers may be missing.
5. Cross-cutting - If a rock cuts through another rock, the cutting one
has to be younger.
Write the name of each Law of Stratigraphy underneath its picture.
Name: _________________
STRATA (Part 1)
1. Decide which of your fossils you want to be the oldest and which are
the youngest. Draw each fossil right here in order from “oldest” to
“newest”. Number each picture.
2. Plan where you will put each one. Write down the colours you will
use in order from the bottom of the container to the top. Beside each
colour write down the number name of each fossil you will put in that
coloured layer.
Name: _________________
STRATA (Part 2B)
1. What would cause deposition layers in real life to be thick?
_____________________________________________________________
_____________________________________________________________
2. What would cause layers in real life to be thinner?
_____________________________________________________________
_____________________________________________________________
3. Why might layers in real life be uneven?
_____________________________________________________________
_____________________________________________________________
4. Draw a fossil from your second coloured layer.
5. Draw the impression it made in the coloured plaster layer.