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
Gravel >2.0 mm Rock that is unconsolidated with fragments that have ...view middle of the document...
(See Figure 4.12 in the textbook.)
1. Montebello, California
2. Bakersfield, California GP poorly graded gravel gravel sand mixure. CL inorganic clay of low to medium plasticity, gravelly clay, sandy silty lean clay.
The five important soil-forming factors are indicated in the following table. Describe why these factors are important in the formation of soil.
Soil forming factor Importance in soil formation
Parent material Parent material is made of rock and minerals. When the other four soil-forming factors act on parent material, it is weathered into smaller particles forming soil. There are many types of parent material with different mineral contents. The Earth is believed to be about three billion years old. Mountains have been created and eroded away and then created again. Seas have covered the land and receded leaving layers of mud, sand and lime carbonate thousands of feet thick. Volcanoes have erupted. Glaciers have formed during long periods of cold weather and melted during long periods of warm weather. Parent material can be rock formed in place or the remnants of rock that was moved by wind, water, ice or even gravity. A variety of parent material can be found in Nebraska ranging from sand in the Sandhill Region to clays in the Missouri and other river bottoms. In the Great Plains, especially in the south, parent materials are primarily associated with ancient seas. These seas came into the region and receded several times, leaving sediment behind, which, over time, became sandstone, limestone and shale bedrock formations. Bedrock soil formations are classified as residuum parent materials and can be exposed and broken down to form soil.
Climate The amount of water entering a soil influences the movement of calcium and other chemical compounds in the soil. Ultimately, if more chemicals are removed, the soils will be deeper and more developed. Precipitation influences vegetation and, therefore, greatly determines the organic matter content of soils. Because of greater precipitation native vegetation included luxuriant growth of the tallgrass prairie. Precipitation is about half that in the east, plants of the shortgrass prairies grow much less abundantly. Thus, soil organic matter content is greater in the east than in the west. Higher temperatures can speed the rate of organic matter decomposition. Temperatures are typically higher in the southern portion of the state than in the northern portion. Because of this trend, organic matter content decreases from north to south. However, the change in organic matter content from north to south due to temperature is minuscule when compared to the change from east to west due to precipitation.
Living organisms The most abundant living organism in the soil is vegetation. Vegetation influences the kind of soil developed because plants differ in their root systems, size, above ground vegetative volume, nutrient content and life cycle. Soils formed under trees...