Law of Superposition, stratigraphic column, volcanic ash, volcano, measure, demonstrate, compare, interpret, observe, apply, analyze, conclude, tephra, lahar, pyroclastic flow, stream gravel, lava flow, landslide, rock fall, mount rainier, Mount Rainier National Park, Living with a Volcano in Your Backyard, Cascades Volcano Observatory
Model depositional processes from volcanically active areas using sediments in a shoebox. Interpret geologic events from layers in a classmate's shoebox model and draw a stratigraphic column graphic. This lesson plan is part of the "Living with a Volcano in Your Backyard" curriculum, created through a partnership between Mount Rainier National Park and the US Geological Survey Cascades Volcano Observatory.
Learn about the types of deposits produced by volcanic processes
Learn about the law of superposition
Apply knowledge of geologic processes to create and interpret a model
Measure and record data to create a stratigraphic column
Earth processes, such as volcanic events, floods, landslides and glaciers, frequently leave behind evidence of their passing in the form of layers known by geologists as deposits. By studying deposits of recent Earth events, geologists are able to look at older deposits and identify the processes that caused them.
One of the fundamental principles of geology is the Law of Superposition. This law states that layers that younger will be deposited on top of layers that are older. This law is a guiding principle of studying rock and soil layers. The Law of Superposition helps geologists determine the relative ages of earth events.
Geologists often portray these deposits in a vertical drawing called a stratigraphic column. Drawing a stratigraphic column can help students visualize a sequence of earth events.
Materials include a photo illustration for constructing shoebox stratigraphic column, a student list of materials and the deposit each represents, student worksheets for interpreting the column, and a graphics page illustrating layers at Mount Rainier.
Collect items. See "Shoebox Geologist Recipes" worksheet for a list of items to collect and description of what volcanic deposits they represent.
Assemble each type of rock material in a bucket or in bags. Label your materials for easy access and identification by students- tephra, lahar, forest floor, etc. You might choose to place a selection of materials in one-gallon bags, and deliver them to each student group. If you are conducting the activity in a natural setting, ask the students to collect and label materials.
Instruct students to collect "human artifacts" (i.e. paper clips, buttons, etc.), and to bring a shoebox from home.
The shoebox layers will remain more cohesive if you add powdered quick-drying cement such as Plaster of Paris, at a ratio of approximately four parts rock material to one of quick-drying cement. A light misting of water should be added by students using a spray bottle just after they create each layer in their shoebox. Test this before class to determine how much water students should spray on with the material that you have given to them. Tamping or pressing firmly after each layer will also help the layers to solidify. As an alternative to use of the cementing ingredient, use simple layers of different colors of sand- layers that hold together well and can be identified easily.
Interpreting a Stratigraphic Column of Books and Papers
The Law of Superposition states that layers that are yonger will be deposited on top of layers that are older. Illustrate this concept by having the class build a column of papers and books, followed by the drawing of a stratigraphic column on a projected transparency or board.
You will need:
Class copies of "Shoebox Geologist Recipes" student page
"Layers at Sunrise Ridge on Mount Rainier" graphic
To illustrate the Law, create a stratigraphic column graphic as a class. Multiple students stack papers and books at one central location that is visible to all.
Afterwards, the class describes the events from first to last. Students verbally describe some characteristics of each book or paper layer. During this discussion draw and label the event sequence, from bottom to top, on an overhead transparency or board.
Instruct students to remove one or more books before the stratigraphic column graphic is finished. Ask if there is evidence that the event ever happened.
Discuss some of the geologic processes that might produce layers at Cascade volcanoes. Then, display the "Layers at Sunrise Ridge on Mount Rainier" graphic to show the class a true example of rock and sediment layers. Point out the different types of layers in the section. Refer students to the table on the "Shoebox Geologist Recipes" student page that describes the different layers produced by geologic processes.
Discuss gradual versus catastrophic processes and give examples: soils are formed by gradual processes; tephra deposits are deposited by a catastrophic process.
Modeling Earth Events in a Shoebox
Model the deposition of erosion of various geological processes using ingredients in a shoebox.
You will need:
6-8 copies of "Shoebox Geologist Recipes" student page
6-8 copies of "Shoebox Geologist - Sequence of Events" student page
6-8 copies of "Shoebox Geologist - Interpretation of Events" student page
2-4 tarps (for indoor use only)
Medium to coarse sand
Dry cement powder or rock dust
4 or more varieties of colored sand
Fine white sand
Human artifacts (bottle caps, match sticks, sting, etc.)
18-24 containers for mixing sediments (plastic bags, buckets, or large beakers work well)
Disposable gloves for the students
Spoons for scooping rock materials
Spray bottles with water
Conduct this activity outdoors in a room free of carpets.
Place buckets or bags of materials and water on a resource table so that students can obtain them as needed.
Divide students into 4-5 person groups.
Each group requires a shoebox, containers for water (spray bottles) and for carrying materials to their work area, copies of "Shoebox Geologist Recipes" and "Shoebox Geologist - Sequence of Events" student pages. Students write their group number on the "Shoebox Geologist - Sequence of Events" student page.
Students should work in groups to decide the type, order, and thickness of layers that they wish to construct in their shoebox. Encourage and model discussion along the following lines: "At the bottom of the box, I will make a stream bed. A thick lahar will flow over the top of the stream bed, followed by rocks from a pyroclastic flow, and a thin layer of volcanic ash. On top of that I will put a layer of rocks from a lahar, then two more layers of thick volcanic ash- each of different colors. Then, I will add rocks from another lahar, some human artifacts, another ash layer, and then forest floor on top."
Students list their chosen layers in sequence from oldest to youngest (bottom to top) on the "Shoebox Geologist - Sequence of Events" student page. On the "Shoebox Geologist Recipes" student page, students circle their necessary ingredients, and place numbers on the page margin to show the order in which ingredients are to be added.
Place the "oldest" layer on the bottom of the shoebox and tamp or press firmly to solidify. Mist lightly with water to activate the Plaster of Paris. Continue layering the materials, pressing firmly, and lightly misting each layer according to the desired sequence of events. Be careful not to add too much water. The boxes should be damp but not dripping.
Allow shoeboxes to dry for 2-3 days.
Interpreting Volcanic Events from Layers in a Shoebox Model
Interpret the shoebox layers by drawing a graphic representation of a stratigraphic column.
You will need:
Copies of "Shoebox Geologist Recipes" student page
Copies of "Shoebox Geologist - Interpretation of Events" student page
After the shoebox models are dry, students exchange their model for that of another group.
Give each group a "Shoebox Geologist-Interpretation of Events" student page. Each group should also have at hand their "Shoebox Geologist Recipes" student page distributed previously.
Instruct students to cut open the sides of the boxes carefully, using scissors, making any notations about initial observation of geologic events on the back of the student page.
Measure the thickness of each layer with a ruler, and then record their observations on the "Shoebox Geologist-Interpretation of Events" student page. Note: If the model is too dry and crumbly, use water from a spray bottle to dampen it.
Instruct students to use the table from the "Shoebox Geologist Recipes" student page to identify the layers. Students should interpret the order of geologic events using the stratigraphic columns and the "Law of Superposition."
Return the "Shoebox Geologist-Sequence of Events" student pages from the previous section to the appropriate groups. Direct students to compare their interpretations to the list of actual events from the group that constructed the model.
Discuss as a class why interpreting layers is important. What are some difficulties in interpreting layers? Which layers were gradually deposited and which were deposited catastrophically?
For assessment, review the stratigraphic columns and look for evidence of students recognition that each layer represents a geologic event. Students should be able to interpret the order of events by noting that the oldest evidence exists at the bottom while products of younger events are found at the top. Assess application to real-world situations by assigning interpretation of an additional ready-to interpret geology shoebox. For older students assign and interpretation of layers at a local road cut or stream cut in your community.
Volcanic events, floods, landslides, and glaciers have left behind deposits that can be studied to understand the processes that caused them.
Stratigraphic columns can be created in a graduated cylinder or beaker.
Photograph Your Shoebox: Take photographs of each opened shoebox and instruct students to label each layer using a computer graphics program.
Kitchen Layers in a Jar: Make your own layered sequence out of kitchen ingredients. Use ingredients such as cornmeal, cinnamon, oatmeal, flour, decorative sprinkles, and different colors of sugar to represent volcanic deposits (lahars, tephra, lava) and glacial or stream deposits.
Fill a graduated cylinder or tall jar with layers of different ingredients. Add each ingredient so that layers are of different thickness. Each layer should contain material that looks similar to the type of deposit it represents.
Instruct students to write and apply labels of each layer with a piece of masking tape.
Instruct students to write a story about the series of events that occurred to deposit these layers.
Stratigraphic Columns from Other Regions: Use library or internet research to find stratigraphic columns of other geologic regions. Discuss how they are alike or different from stratigraphic columns in volcanic landscapes.
Write a Geologic Story: Instruct students to write the geologic story of the events that happened at the site of their shoebox geology.
Cas, R.A.F., and Wright, J.V., 1987, Volcanic successions modern and ancient-a geological approach to processes, products and successions: Allen and Unwin, London, 528 p.
Fisher, R.V., and Schmincke, H.U., Pyroclastic rocks: Springer-Verlag, New York, 1984, 472 p.
Scott, K.M, Vallance, J.W., and Pringle, P.T., 1995, Sedimentology, behavior, and hazards of debris flows at Mount Rainier, Washington: U.S. Geological Survey Professional Paper 1547, 56 p., 1 pl.
Vallance, J.W., and Scott, K.M., 1997, The Osceola Mudflow from Mount Rainier: sedimentology and hazard implications of a huge clay-rich debris flow: GSA Bulletin, February, 1997, v. 109: no.2: p. 143-163, 6 tables.
Zehfuss, P.H., Atwater, B.F., Vallance, J.W., Brenniman, H., Brown, T.A., 2003, Holocene lahars and their by-products along the historical path of the White River between Mount Rainier and Seattle: in Swanson, T.W., ed, Western Cordillera and adjacent areas: Boulder, Colorado, Geological Society of America Field Guide 4, p. 209-223.
deposit, Law of Superposition, stratigraphic column