An example of a sandwich that shows layers of food to represent layers of rock

Overall Rating

Add your review
Grade Level:
Upper Elementary: Third Grade through Fifth Grade
Lesson Duration:
30 Minutes
State Standards:
State: Colorado Subject: Science Grade Level: 4th

State Standards
2.2.a - Explain what fossils say, the similarities between fossil and living organisms
2.2.b – Interpret evidence for past environments
Additional Standards:
Common Core 4th Grade Science Standards:
2.2 Comparing fossils to each other or to living organisms reveals features of prehistoric environments and provides information about organisms today
Thinking Skills:
Remembering: Recalling or recognizing information ideas, and principles. Understanding: Understand the main idea of material heard, viewed, or read. Interpret or summarize the ideas in own words. Applying: Apply an abstract idea in a concrete situation to solve a problem or relate it to a prior experience. Analyzing: Break down a concept or idea into parts and show the relationships among the parts. Creating: Bring together parts (elements, compounds) of knowledge to form a whole and build relationships for NEW situations. Evaluating: Make informed judgements about the value of ideas or materials. Use standards and criteria to support opinions and views.

Essential Question

What is a Stratigraphic Column? What is a Cross Section? How do rock layers relate to a Stratigraphic Column?


1. Students will learn about the specific layers of the Florissant Formation in which fossils have been found
2. Using food to represent each rock layer in a stratigraphic column
3. Using a plastic knife to cut the sandwich in half and show a cross section of their formation


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.



·         Wheat bread (Wall Mountain tuff)

·         White bread (lahar)

·         Multigrain bread (upper pumice conglomerate)

·         Gummy worms (fossil insects)

·         Gold fish (fossil fish)

·         Raisins or lettuce (fossil plants)

·         Chocolate chips/ Crunch bites (debris flow material)

·         Paper plates

·         Laminated handouts of Florissant Formation

·         Straws (for core samples)

·         Napkins


Here is a double sided PDF of the Florissant Formation Stratigraphic Column. One side is the actual Stratigraphic Column and the other side is a guide for where the food items go along with their age.

Download Florissant Formation

Lesson Hook/Preview

Students will recreate the Florissant Formation Stratigraphic Column using food materials. Each food item will represent a specific layer of the Florissant Formation. This lesson can be adapted with any food item, also any Stratigraphic Column.


1. Hand each pair of students a napkin/plate and a slice of wheat bread, which represents the Wall Mountain Tuff.

2. Each pair can work at their own pace creating their Florissant Club Sandwich. However, make sure the students follow the order of the stratigraphic sequence.

3. Instruct the students to refer to the laminated handouts while building their stratigraphic column (sandwich). Tell them that the oldest layer is on the bottom and the youngest layer on top. Therefore, they must build their sandwich from oldest to youngest (bottom to top).

4. The sequence of the sandwich, bottom to top, should be as follows on the Florissant Formation sheet.

5. Once the students are done building their sandwich, instruct them to cut it in half so that they can have a cross section. Have them correlate each food layer to the rock layer on the handout.

6. Give each student a clear plastic straw piece and instruct them to take a core sample of their sandwich as well.

7. The students can then eat their half of the sandwich if they wish to.


·         Stratigraphy - the branch of geology concerned with the order and relative position of strata and their relationship to the geological time scale.

·         Formation - an isolated, scenic, or spectacular surface rock outcrop.

·         Stratigraphic column - a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area

·         Tuff - a light, porous rock formed by consolidation of volcanic ash.

·         Lahar - a destructive mudflow on the slopes of a volcano.

·         Debris flow - a moving mass of loose mud, sand, soil, rock, water and air that travels down a slope under the influence of gravity.

Assessment Materials


This can be done individual or as a group discussion.

  1. Which layer is the oldest? Why?
  2. In which layers of the formation do we find most fossils?
  3. Based on the fossils you find in the Florissant Formation, what type of environment do you think existed at the time of deposition?
  4. Based on the environment, where do you think we would find relatives of the fossils today?
  5. Can you correlate certain layers with geologic events?

Rubric/Answer Key


If done as a group setting, encourage students to use their critical thinking skills and think of more than one answer or give examples of their answers, if possible.

  1. Wall Mountain Tuff

  2. Middle Shale and Lower Mudstone Unit

  3. Warm, wet environment (redwood trees need a lot of moisture to stay alive)

  4. Northern California/Oregon/Small part of China for the Redwood trees. Insects and plants around the equator

  5. Yes, mostly during volcanic events

Supports for Struggling Learners

In depth description of Stratigraphy:


Description with pictures on the law of superposition:

Contact Information

Email us about this lesson plan

Last updated: January 30, 2019