Activity Details




Students will

  • Learn how natural forces shape the rock layers of the Earth’s crust.



  • One slice of white bread, as one rock layer
  • Two paper plates, for holding the sandwich
  • Two tablespoons of peanut butter (crunchy) mixed with raisins, for filling
  • One slice of whole wheat bread, as a second layer
  • Two tablespoons of jam or jelly, for filling
  • One slice of dark rye bread, as the third and final layer
  • Wooden tongue depressor or plastic knife, for cutting the sandwich
  • Measuring spoons for serving jelly



Note:You will be working in pairs as instructed by your teacher / guide. In this activity you will, together, make and manipulate a sandwich in the same way that natural forces shape layers of rock.

  • Place the white bread on a paper plate.
  • Next, spread the peanut butter on the white bread.
  • Next, add the whole wheat bread and cover with jelly.
  • Next, add the rye bread.
  • Call the layers just what they are.
    Note: If you are familiar with the various rock types, use imaginative rock names such as “wholesome shale” for whole wheat bread or “sticky conglomerate” for chunky peanut butter.
  • As one of you add the various parts to your sandwich, which represent various layers of earth’s crust, the partnering student keeps track of the progress by drawing a diagram on the chalkboard of the various layers.
    Note:All student pairs should have identical three layer sandwiches. The white bread (the oldest layer) at the bottom, the whole wheat bread (the next layer) in the middle and the rye bread (the newest layer) at the top.
  • Think and Discuss:When all the sandwiches are assembled, discuss the concept of how some rocks in the Earth’s crust are layered.
    Note: Geologists rarely find rocks as flat and horizontal layers as you see in the sandwich. Often they will see layers that are bent or broken.
  • To understand this concept, gently bend your sandwich to form an arch.
    Note:Always keep the oldest layer, white bread, on the bottom. This structural form is called an “ANTICLINE.”
  • Next, bend the sandwich to form a trough.
    Note:Again, the white bread is at the bottom. This structure is called a “SYNCLINE.” Adding pressure to a horizontal layer can cause it to bend up or down, one-way in which mountains and valleys are formed.

Note:Sometimes blocks of the Earth’s crust move up or down along major fractures or “FAULTS.” This type of movement can cause EARTHQUAKES.

  • Cut their sandwich in half and move one half up or down.
  • Determine which side moved up or down. Either the left side moved up and the right side moved down or the other way around.
    Note:You can see this movement because of the different layers of the sandwich. This is called a “VERTICAL FAULT.”
  • Draw a picture of this type of fault movement.
    Note:You can also create another type of fault, a “LATERAL FAULT.”
  • Slide the two parts of the sandwich past each other (sideways) on the same level to produce lateral fault movement.
    Note:This type of movement causes earthquakes on the San Andreas Fault in California.


Q1.What is the oldest part of your sandwich? 




Q2.What is the youngest layer? 




Q3.If the middle of the sandwich layers bend upward, what type of structure do you have? 




Q4. If the middle layers of the sandwich layers bend downward, what type of structure do you have? 




Q5.If the sandwich is broken (cut), look at the relationship of the various layers to tell what type of fault movement you have.





Teacher Notes




  • Foods are commonly used as instructional tools and in many hands-on activities presented here. A review of food use to demonstrate Earth-science concepts is presented by Francek and Winstanley (2004); however, they also note that there are potential problems associated with using food as an instructional tool. One of the main safety issues is that some foods, such as chocolate or peanut butter, could cause a student to have an allergic reaction. It is important that the instructor inform students and parents that you will be conducting a class activity that involves food, so that they can tell you if there are any health problems that should be addressed. Students with allergies to certain food groups may participate in the activities through observation, as long as their allergies are not induced by touch or smell of the food items used.
  • Remember, when doing any activity that involves the use of chemicals, be sure to use the proper Personal Protective Equipment (PPE), such as gloves, safety glasses, and laboratory coats.


Tips and Tricks:


  • The process of finding or exploring for a mineral deposit, extracting or mining the resource, recovering the resource, also known as beneficiation, and reclaiming the land mined can be described as the “life cycle” of a mineral deposit.
  • Mineral deposits are the source of many important commodities, such as copper and gold, used by our society, but it is important to realize that mineral deposits are a nonrenewable resource. Once mined, they are exhausted, and another source must be found. New mineral deposits are being continuously created by the Earth but may take millions of years to form.
  • Mineral deposits differ from renewable resources, such as agricultural and timber products, which may be replenished within a few months to several years.
  • The technical definition of a mineral is a naturally occurring, inorganic, homogeneous solid with a definite chemical composition and an ordered atomic arrangement. In more general terms, a mineral is a substance that is:
    (1) made of a single element like gold (Au) or a compound of elements like salt (NaCl) and/ or
    (2) a building block of rock (for example, granite is composed primarily of the minerals quartz and feldspar).
  • Minerals may be metallic, like gold, or nonmetallic, such as talc.
  • Oil, natural gas, and coal are generally considered to be “energy minerals” and are not discussed in this report.
  • A mineral deposit is a mineral occurrence of sufficient size and grade (concentration) to enable extraction under the most favorable conditions.
  • Two cycles determine how mineral deposits are formed— the ROCK CYCLE and the TECTONIC CYCLE.
  • Heat from the Earth’s interior melts some of the rocks in the crust (the upper part of the lithosphere).
  • Molten rocks lower in density than the surrounding cooler material rise toward the Earth’s surface and eventually cool and harden near to or on the surface.
  • The composition, temperature, pressure, and cooling process of the molten material determine the minerals and rock types formed.
  • These are called IGNEOUS ROCKS and contain original or primary minerals.
  • When these rocks are subjected to chemical and physical processes, such as freezing and thawing, they break apart into smaller fragments forming sediments.
  • These smaller particles that compose the sediments can be physically transported and re-deposited by gravity, water, and wind.
  • If the re-deposited particles are bound together by compaction or cementation (formation of new secondary minerals in the spaces between the loose particles), SEDIMENTARY ROCKS are formed.
  • In regions where the Earth’s interior temperature and pressure are high enough to change the chemical composition and mineralogy of buried igneous or sedimentary rocks, without completely melting them, METAMORPHIC ROCKS are formed.
  • Distinct groups or assemblages of minerals are typically associated with the formation of each of the three major rock types—igneous, sedimentary, and metamorphic rocks.
  • PLATE TECTONICS play a major role in the processes of mineral and rock formation.
  • In geologic terms, a plate is a large, “rigid” slab of solid rock.
  • The word tectonics comes from the Greek root “to build.”
  • The term plate tectonics refers to the process by which the Earth’s crust is formed and moved.
  • The theory of plate tectonics states that the Earth’s outermost layer, the crust, is fragmented into a dozen or more plates of various sizes that are moving relative to one another as they are slowly transported on top of and by hotter, more mobile material (Kious and Tilling, 1996).
  • Scientists now have a fairly good understanding of how the plates move and how earthquake activity relates to such movement.
  • Most movement occurs along narrow zones between plates where the effects of tectonic forces are most evident.

There are four types of plate boundaries:

  • Divergent boundaries—where new crust is generated as the plates pull away from each other.
  • Convergent boundaries—where crust is destroyed as one plate dives under another.
  • Transform boundaries—where crust is neither produced nor destroyed as the plates slide horizontally past each other.
  • Plate boundary zones—broad belts in which boundaries are not well defined and the effects of plate interaction are unclear (Kious and Tilling, 1996).

Hands-On Activities

  • This activity is one of a set of activities designed to educate students about geology, plate tectonics, and mineral resources and how mineral resources are found, extracted, processed, and used.
  • These activities are suited for the entire K-12 grade level range, but some may be best suited for the 5-8 or 9-12 grade levels (table 3). The activities are as follows:

Basic Geology—Concepts

Exploring for Minerals

Extracting Minerals

Uses of Minerals

Mineral Resources and Economics

Some Suggestions for the Activity:

  • Have students work in pairs. Each pair will need a paper plate with the above ingredients.
  • Tell the students you will show them how to make and manipulate a sandwich in the same way that natural forces shape layers of rock.
  • Have the students call the layers just what they are. If you have been studying rocks and the students are familiar with the various rock types, have them name the various layers of the sandwich. They can use imaginative rock names such as “wholesome shale” for whole wheat bread or “sticky conglomerate” for chunky peanut butter.
  • All students should have identical three layer sandwiches.
  • This project has other ways to demonstrate how the Earth is layered and how the various layers can be deformed; be creative and have fun! Some of the questions that can be addressed are:

Answers to questions

  • Q1.Bottom layer, white bread, first piece used or whatever name given by the students for the layer.
  • Q2.Top piece, rye bread, last piece to be put on or whatever name given by the students for the layer.
  • Q3.Anticline
  • Q4. Syncline



Additional Resources:




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