ERN Item Type:
- Classroom Activities
Are soils like M&Ms™? Yes! Typical soil colors are red, brown, yellow, or black. These colors are often not the color of the minerals in the soil but coatings of iron oxides (Fe203, FeOOH, and so on) or organic matter on particles. The minerals beneath are often quartz or feldspar, which are grey. Soil scientists can identify where the water table is even when the soil is not saturated. Consider the M&Ms™ again. What is the chance that the now-white ones will turn red again? Slim to none. Soil is the same. Once the red (rusty) colors due to iron oxides have been removed and the soil is gray, it is unlikely that the particles will become coated (turn red) again. In this activity, students record canned/jarred soil mixtures for color changes and bubbles.