University of Phoenix Material
Soil and Glaciers Worksheet
From Visualizing Earth Science, by Merali, Z., and Skinner, B. J, 2009, Hoboken, NJ: Wiley. Copyright 2009 by Wiley. Adapted with permission.
Size grades of soil are named sand, silt, and clay, which includes colloids. Size grades are defined using the metric system. Use Figure 4.8 from the textbook to fill in the following chart. Specify the type and size and description of the particle. In some cases, particle size will be less than some value or greater than another value. For instance, gravel is greater than 2.0 mm.
|Name |Size |Description ...view middle of the document...
002 |Clay is a soft, loose, earthy material containing particles with a grain size of less than 4 micrometres |
| | |(μm). It forms as a result of the weathering and erosion of rocks containing the mineral group feldspar |
| | |(known as the ‘mother of clay’) over vast spans of time ("What Is Clay?", 2007-2015). |
|Colloids |0.000001 |Particles intermediate in size between those found in solutions and suspensions can be mixed such that they|
| | |remain evenly distributed without settling out. These particles range in size from 10-8 to 10-6 m in size |
| | |and are termed colloidal particles or colloids. The mixture they form is called a colloidal dispersion. A |
| | |colloidal dispersion consists of colloids in a dispersing medium (Helmenstine, 2015). |
Soils have been classified according to a system developed by soil scientists and the U.S. Soil Conservation Service. Using this classification system of soil orders, pick two locations on Earth, one in your current area and another area, and describe the order and the conditions that define it. (See Figure 4.12 in the textbook.)
1. Inceptisols (from Latin inceptum, "beginning") are soils that exhibit minimal horizon development. They are more developed than Entisols, but still lack the features that are characteristic of other soil orders. Although not found under aridic climate regimes, Inceptisols nevertheless are widely distributed and occur across a wide range of ecological settings.They are often found on fairly steep slopes, young geomorphic surfaces, and on resistant parent materials. Land use varies considerably with Inceptisols. A sizable percentage of Inceptisols are found in mountainous areas and are used for forestry, recreation, and watershed. Inceptisols occupy an estimated 15% of the global ice-free land area – only the Entisols are more extensive. In the US, they occupy ~9.7% of the land area. Inceptisols support ~20% of the world's population, the largest percentage of any of the soil orders (University of Idaho , n.d.).
2. Vertisols (from Latin verto, "turn") are clay-rich soils that shrink and swell with changes in moisture content. During dry periods, the soil volume shrinks, and deep wide cracks form. The soil volume then expands as it wets up. This shrink/swell action creates serious engineering problems and generally prevents formation of distinct, well-developed horizons in these soils.Globally, Vertisols occupy ~2.4% of the ice-free land area. In the US, they ccupy ~2.0% of the land area and occur primarily in Texas (University of Idaho , n.d.).
The five important soil-forming factors are indicated in the following table. Describe why these factors are important in the formation of soil.