in Earth science

KILEY CRUSE World-Herald Sta Writer

If you were to take a cross section of the soil in your backyard, you’d nd there are different layers, each with a purpose.

At the very top is the organic material. This is the upper layer of topsoil which is made up of mostly of grasses, dead leaves, small rocks, twigs and other decomposing organic material.

Next comes the topsoil. Another name for this layer is the humus layer. It contains both organic matter and decomposed materials. The topsoil is porous to hold air and water. This is the layer where seeds germinate, roots grow and earthworms live.

Below that is the subsoil. This is harder and more compact than topsoil. It holds more water than topsoil and is lighter in color due to clay being mixed in.

Next is parent material which is formed from bedrock after a long weathering process. This is where the soil layers above will be formed.

Last, we have bedrock. This layer can be made of igneous, sedimentary or metamorphic rock.

As you can see, soil is so much more than the few inches we see when we dig to plant our gardens.

Earth Day is a great time to teach kids about the layers of soil with this edible representation. Gather the ingredients, start layering, and then dig in.

EDIBLE SOIL

• Chocolate and butterscotch chips mixed together

• Chocolate pudding

• Whole Oreos, crushed Oreos

• Crushed graham crackers

• Shredded coconut mixed with green food coloring

• Gummy worms

• Clear cups or glasses

• Spoons

• Sticky post-its or labels

1. Drop a whole Oreo into the bottom of your glass. This represents the bedrock.

2. On top of the Oreo, add a mixture of chocolate and butterscotch chips. This represents the parent material.

3. Carefully spoon chocolate pudding over the chips. This represents the subsoil.

4. Mix together crushed Oreos and graham crackers. Add this mixture over the pudding layer. This represents the topsoil.

5. Stick the gummy worms out of the topsoil.

6. Sprinkle green coconut on top, allowing the worms to peek out. This represents the organic material.

7. Use sticky notes to label your layers.

8. Dig in.

Note: If you want more nutritious alternatives, substitute almonds or another small-type of nuts for the bedrock, yogurt for the subsoil, granola for the topsoil, and several berries for the organic matter on top. You get the idea! Have fun with this one. The kids will love it, even with the modi ed ingredients!