Lesson Plan

Florissant Club Sandwich

Grade Level:
Upper Elementary: Third Grade through Fifth Grade
Subject:
Science
Lesson Duration:
30 Minutes
State Standards:
Colorado Academic Standards for Science: 4th grade; 2.2a- Explain what fossils say, the similarities between fossils and living organisms. 2.2b- Interpret evidence for past environments.
Thinking Skills:
Understanding: Understand the main idea of material heard, viewed, or read. Interpret or summarize the ideas in own words. Creating: Bring together parts (elements, compounds) of knowledge to form a whole and build relationships for NEW situations.

Essential Question

How can we relate to the deposition of the Florissant Formation?

Objective

Students will learn about the specific layers of the Florissant Formation in which fossils have been found. By using food items to represent specific layers of the Florissant Formation, they will recreate the formation. Lastly, they will use a plastic knife to cut the sandwich in half and show a cross section of their formation.

Background

Stratigraphy is the study of rock beds (layers) and their ages in relation to one another. The law of superposition states that any rock layer underlying another must be older than the one above it and vice versa. Together, these layers of rock form what is called a formation. In order to study such formations in detail, geologists sketch what is called a stratigraphic column, a representation of the vertical location of rock beds in a given area.
Fossils are incredibly useful in helping geologists obtain relative ages of rocks. Often times, just by identifying the fossil types present in a rock, paleontologists can get a fair estimate of the age of a rock layer. At Florissant Fossil Beds National Monument, geologists have constructed a stratigraphic column of the Florissant Formation to better understand the sequence of geologic events that occurred here 34 million years ago.

Preparation

You will need:

  • A plate

  • Napkins or paper towels

  • A clear plastic straw (best to use a thick one so it doesn't bend)

  • A plastic knife or popsicle stick

  • Wheat bread (Wall Mountain Tuff)

  • White bread (lahar)

  • Multigrain bread (Upper Pumice conglomerate)

  • Ham (fossil insects in Middle Shale Unit)

  • Turkey (fossil fish in Upper Shale Unit)

  • Lettuce (fossil plants in Lower Shale Unit)

  • Cheese (Caprock conglomerate)

  • Diagram of the Florissant Formation (provided)

  • Pictures of: Pikes Peak Granite, Wall Mountain Tuff, lahar, shale, petrified wood, and Caprock conglomerate

You can replace any of the food items you don't have or don't like with something else. Just make sure that you have different items to represent each rock layer.

Materials

A diagram of how the sandwich parts represent the layers of the Florissant Formation.

Download Sandwich Column

A diagram showing how the different layers of the Florissant Formation relate to each other.

Download Florissant Formation Stratigraphic Column

Lesson Hook/Preview

Stratigraphy is the study of rock layers (called beds) and their ages in relation to each other. The law of superposition (one of the Principles of Geology) tells us that any rock layer lying underneath another must be older than the one above. And any layer lying above another must be younger than one under it. Basically, the oldest rock sits at the bottom and the youngest is at the top.
In order to study formations (groups of related rock layers found in an area) in detail, geologists make a stratigraphic column. A stratigraphic column is a diagram of the different rock layers and how they are stacked on top of one another. In this activity you will make your own "stratigraphic column" with your sandwich.
At Florissant Fossil Beds, geologists a stratigraphic column of the Florissant Formation to help them understand the sequence of geologic events that happened 34 million years ago.
The oldest rock in Florissant Valley is the Pikes Peak Granite which formed around 1 billion years ago! This rock unit is called a batholith. The granite formed when magma bubbled up into the Earth's crust and cooled while still beneath the surface. We are not including this particular rock in the Florissant club sandwich.

Procedure

The Florissant club sandwich starts with the Wall Mountain Tuff. 37 million years ago a caldera collapsed about 50 miles away from Florissant. This sent a cloud of super-heated ash, gas, and debris like a hurricane rushing through the valley. This created the welded tuff.
#1: Put a slice of wheat bread (or whatever bread you’re using in its place) on the plate. This slice represents the Wall Mountain Tuff. The wall Mountain Tuff is the oldest rock in the Florissant Formation so it is represented at the bottom. The rest of the layers will be stacked on top of it with the youngest on top.
Fossils can be incredibly helpful to geologists finding the relative age of rocks. Paleontologists can often develop an idea of how old a rock layer is by identifying the fossil types found in it. A few of the next rock layers we look at can be identified and their age estimated by the fossils found within them.
#2: Put the lettuce on the first slice of bread. This represents the fossil plants found in the Lower Shale Unit. The Lower Shale Unit is the oldest of the shale deposits. It lies well beneath the other shale units because it was deposited well before them.

#3: Use the diagram of the Florissant club sandwich and the stratigraphic column of the Florissant Formation to make the rest of the sandwich. Keep reading for the story of each layer and how it was deposited. As you make your sandwich remember, the oldest goes at the bottom and the youngest goes on the top.

The first Ancient Lake Florissant was formed in the Florissant Valley. This lake deposited the Lower Shale Unit. The lettuce represents the various fossil plants found in this unit. Later on, the lake drained out and giant redwood trees took root. These massive trees grew along a creek that ran through the valley. Then a volcanic mudflow, called a lahar, covered the bottoms of the trees. Over time this preserved the giant petrified stumps now found on the Petrified Forest and Ponderosa loops at Florissant Fossil Beds National Monument.
After the stumps were buried, Ancient Lake Florissant formed again as another lahar created a natural dam blocking the creek. This resulted in the Middle Shale Unit. At some point a debris flow from the same nearby volcano filled in much of the lake creating the Caprock conglomerate. The lake continued to deposit more shale leaving behind the Upper Shale Unit. Finally the lake was buried when a big eruption from the Guffey Volcanic Complex completely filled it up leaving the Upper Pumice Conglomerate. This is the youngest rock layer of the Florissant Formation and sits at the very top of the stratigraphic column.
#4: Look at the Florissant club sandwich diagram to see how the layers should be ordered. Once the sandwich is made use the plastic knife or popsicle stick to carefully cut it in half. Now you have a cross section of your sandwich. Take a look at the layers inside. Can you relate each layer in your sandwich to the rock layers in the stratigraphic column?

Now you have a cross section of your sandwich. Can you relate each layer of your sandwich to the layers of the Florissant Formation?

#5: Take the plastic straw and push it through the top of one half of the sandwich. Push it all the way through to the other end of the sandwich and then pull the straw out.
You now have a core of your sandwich. You should be able to see the different layers stuck in the straw.
#6: Enjoy your sandwich!

Vocabulary

  • Stratigraphy: noun; geology that deals with the beginnings, composition, distribution, and succession of the layers of rock in the earth's crust

  • Formation: noun; a bed of rocks or series of beds recognizable as a unit 

  • Stratigraphic column: noun; a diagram showing the rock layers from a specific area

  • Tuff: noun; a light porous (full of air pockets) rock formed by solidified volcanic ash

  • Lahar: noun; a landslide of wet volcanic debris on the side of a volcano or the deposit left behind by such a landslide

  • Debris flow: noun; wet masses of soil and debris such as fragmented rock that rush down mountainsides

Assessment Materials

Reflection

  1. Which layer is the oldest? How can you tell?
  2. Based on the fossils that are found in the Florissant Formation, what kind of environment do you think existed at the time of deposition?
  3. In what type of modern environment do you think we would find relatives of the fossils found here?
  4. Can you relate each layer to a geologic event that occurred in Florissant Valley?

Rubric/Answer Key

  1. The Pikes Peak Granite is the oldest rock found in Florissant Valley. We know this beause it is found at the bottom. In your sandwich, the Wall Mountain Tuff is the oldest rock and you can tell that it is oldest because it is the bottom-most layer of your sandwich.
  2. At some point a redwood forest grew in Florissant Valley leaving behind the petrified stumps. A shallow lake also formed leaving behind the fish fossils. We can also tell that there was a volcano nearby because of the lahar and other volcanic rocks.
  3. We would find relatives of the redwood trees on the coast of California. Relatives of other plants can be found in many places across the planet including China and Mexico!

Additional Resources

Check out our other Florissant Club Sandwich page for step by step instructions with pictures!

Contact Information

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Tags: geology geology activity geologic formations geologic layers geologic history geological geologic principles

Last updated: August 16, 2022