Learner Express: Modules for Teaching and Learning
On the Big Island of Hawaii, geologist Oliver Chadwick, of the University of California at Santa Barbara, and geologist Andy Kurtz, of Boston University, dig a pit. By handling the soil directly, they can learn a great deal about its components: sand, silt, and clay. The varying proportions of these materials give the soil a layered appearance. Near the top of a soil profile, the color is usually darker due to a higher proportion of organic material. Scientist Elissa Levine of the NASA Goddard Space Flight Center notes the importance of the organic material in holding water. In Massachusetts, scientist Britt Argow and teacher Joe Reilly compare a pit profile to the one in Hawaii. They find that the chemical weathering of granite as the source rock makes a different kind of soil than lava rock. Rock type, the age of the soil, vegetation, and climate—all contribute to differences in soil. Run Time: 00:05:43
Grades 5-8 Standard D. Soil consists of weathered rocks and decomposed organic material from dead animals, plants, and bacteria, that have different chemical compositions and textures.
Soil Formation—Physical and Chemical Weathering
The Role of Sand, Silt, and Clay Components in Soil Function