peanut butter- chunky (may substitute marshmallow fluff especially if a student has peanut allergy)
Note- Each lab table makes one earth layer sandwich. Use the following story as students build their geologic sandwich.
White sand erodes from upper rocks and
layer - Use the plastic knife to spread chunky peanut butter or marshmallow fluff, on the white bread. You may add chocolate chips or raisins to represent the eroded materials. Over many years, the river erodes brown
them downstream. Again, the velocity of the water slows as the river widens and the silt gradually drops to the bottom. This eventually forms a sedimentary rock called shale. Third layer –
Add a slice of wheat bread for the shale. Meanwhile, glaciers are melting on the
Earth causing the ocean to rise and cover
the area. Millions of tiny marine organisms
and shells begin to line the ocean floor. After many years, the ocean recedes and shells have cemented together forming a layer of rock
called limestone. Fourthlayer – Use the plastic knife to spread jelly (limestone) on the wheat bread. Many fossils can be found in this layer. Add candy worms or fish to the jelly. Finally, a layer of brown sand is blown over the entire area. There has been a severe drought and mighty winds have sandblasted large, brown boulders with small bits of rocks. In time this
layer will become brown sandstone. Sixth layer –
Add a slice of dark bread for the brown sandstone. The geology sandwich is now complete! Follow the PBJ Geology Rocks directions to complete the lab.
Students pretend to be geologists and use a plastic straw or a section of small-diameter plastic pipe to take a “core sample” of the layers. Have the students examine the core and identify the layers. Relate this to real core samples that help
determine the composition and historical sequence of the Earth’s formation.
Students will bend and “fold” the sandwich to relate this model to the formation of mountains as plates collide. Later they will cut their sandwich in half and force one half to “subduct” under the other. Students visualize the interior layers of mountains, documenting how the order of layers can change. After creating a subduction zone, students take another core sample and compare the results.
PBJ Geology Rocks LAB
Name ______________________ date ____________
Objective: Simulate the history of various geological formations by building a layered sandwich. This will model sedimentary rock, fossils, core sampling, anticline, syncline, faulting, uplift, and a subduction zone.
After building your geological sandwich and taking a core sample, sketch and label what your core sample looks like in the box below.
When geologists study rocks, they rarely find them flat and horizontal. Often they will see layers that are bent or broken. To illustrate these structures gently bend your sandwich to form a hill. (Keep the oldest layer on the bottom.) Sketch and label your hill in the space provided.
This is called an ANTICLINE.
Now, bend your sandwich to form a trough. (Bend it in the opposite direction than you did for the anticline.) Sketch and label your trough in the space provided.
This is called a SYNCLINE.
Mountains and valleys are formed this way.
Sometimes the crust of the earth moves up or down as it pushes into other pieces of earth at a subduction zone. In part, this movement causes earthquakes. Cut your sandwich in half and move one half up or down.
Hold the two halves up in front of you. Which side moved up or down? Make sure to force one half to “subduct” under the other half.
Sketch your sandwich now, showing the movement up or down. (Either the left side moved up or the right side moved down or the other way around. You can see this movement because of the different layers of the sandwich.)
This is demonstrates the uplift of mountain building along a convergent boundary.
Now use the straw to take another core sample through the thickest part of your model.
Sketch and label the core sample in the box below.
Subduction Zone Core Sample
Use the space below to describe how this core sample is different from the first core sample you took. Remember to explain some of the geological process that produced the changes.