Spread a thin layer of butter on one side of all the slices of bread. Select one of the slices of bread as the base for the geologic column sandwich. A slice of wheat or multigrain is a good choice as it is made from the most natural ingredients.
Put a layer of chocolate spread onto the bread. This can represent single-cell organisms that lived on earth millions of years ago.
Place a slice of bread on top of the chocolate. Put a layer of shrimp on top of the bread. Explain that early versions of today's shrimp were on earth 500 million years ago.
Place another slice of bread on top of the shrimp and put another sandwich filling on top. Evaluate the age of the filling, or the age it represents. For example, lettuce can represent vegetation that rotted to make coal more than 300 million years ago, while turkey can represent the age of the dinosaurs.
Continue to build your column sandwich by using ingredients such as peanut butter, cheese, jelly and tomatoes. Place the last slice of white bread on top. Use a sharp knife and carefully cut through the multilayers. Separate the two columns so the students can clearly see the layers.