Module 2 • Geology: A Time and Place My Soil Profile
Soil scientists use soil pits to identify the soil horizons in a given area. As they dig into the earth, they discover the layers of soil. The distribution of these layers is what gives the soil it’s “profile.”
As a class, you will dig your own soil pit to determine the soil profile!
Materials shovels
garden trowels work gloves
specimen bottles with labels (at least three for each group) double-sided tape measuring tape
Procedure
1. Begin by marking off a rectangular area about 2 feet by 3 feet (approximately 60 to 100 centimeters). This size is large enough to provide relatively easy access by everyone in your class, taking turns.
Carefully dig out the soil in the area you have marked off. Use as flat a shovel as is practical, and take care around the edges to dig straight, smooth vertical cuts. You want to disturb the soil layers as little as possible at the edges of your pit. The center can be dug with less care.
2. A complete soil profile extends from the surface of the soil to bedrock. You may dig a shallow pit to analyze just the top layers of the soil in your area. Watch the edges of your pit to determine how many layers are exposed.
3. Once you have dug your pit, extend a tape measure from the top layer to the floor of the pit. Each group may take turns collecting data and samples from the pit as outlined below.
Measure each layer in centimeters from the top to the bottom and write the measurements below.
4. Use a clean specimen bottle to collect soil from each of the layers. Be sure to label each specimen with the correct layer number.
5. Back in the classroom, cut out the soil card below to create a soil sample. Attach a short strip of double-sided tape to the card. Pull back the tape at the top to expose some of the sticky tape and place soil from the surface horizon to represent the depth of this soil. Pull back the tape for each additional layer one at a time, following the same procedure.
6. Snap a digital photo of your card and post it to the Zone 02 in Explore at PolarHusky.com