LabWorksheet07_GettingtoKnowtheSoils

.pdf

School

Santa Monica College *

*We aren’t endorsed by this school

Course

5

Subject

Geography

Date

Jun 4, 2024

Type

pdf

Pages

7

Uploaded by CaptainPigeon3181

Name: _____________________________ Lab Worksheet 7: Getting to Know the Soils GEOG 5, Instructor: Joy Fritschle This lab is in three parts: in part 1, you will examine soil horizons, color, and texture; in part 2, you will study several different soil orders from around the world; and in part 3, you will investigate the soils at a specific location in the U.S. Part 1: Soil Properties: Horizons, Color, and Texture In this part of the lab, you will more closely examine the key properties of soils including their horizons, color, and texture. The process of soil formation generally involves the downward movement of clay, water, and dissolved ions. The common result of that is the development of chemically and texturally different layers known as soil horizons . The commonly developed soil horizons are as follows: ➢ O: the layer of organic matter ➢ A: the layer of partially-decayed organic matter mixed with mineral material ➢ E: the eluviated (leached) layer from which some of the clay and iron have been removed to create a pale layer that may be sandier than the other layers ➢ B: the layer of accumulation of clay, iron, and other elements from the overlying soil ➢ C: the layer of incomplete weathering ➢ R: the parent material or bedrock English Cleveland
1. Based on the descriptions provided in the table on the next page, label the soil horizons shown on each of the four soil profile diagrams . (remember: not all soils have all the horizons present!) (2 pts) Soil Horizon Labeling Profiles and Descriptions Profiles and Descriptions Soil Profile 1. Few horizons have formed because the parent material was recently exposed to weathering. There is some biological weathering activity initiated by moss growth. Soil Profile 2. This is an arid environment with low rates of weathering. Caliche (calcium carbonate) deposits are found in the B horizon. Soil Profile 3. This is a well-developed soil in a temperate environment. Soil Profile 4. This is a soil in a tropical environment with aluminum oxide deposits (bauxite) in the B and C horizons. R Horizon R Horizon C Horizon B Horizon A Horizon E Horizon A Horizon E Horizon R Horizon R Horizon A Horizon E Horizon B Horizon C Horizon C Horizon A Horizon E Horizon B Horizon C Horizon
Soil color is another physical property of soil. The mineralogy of the parent material and the rates of weathering are the two main factors that determine a soil’s color. Minerals and Common Soil Colors Material Formula Common Soil Color goethite FeO(OH) yellow, strong brown hematite Fe 2 O 3 red lepidocrocite FeO(OH) reddish-yellow, red ferrihydrite Fe(OH) 3 dark red glauconite K(Si x Al 4-x )(Al,Fe,Mg)O 10 (OH) 2 dark gray iron sulfide FeS black pyrite FeS 2 black (metallic) jarosite KFe 3 (OH) 6 (SO 4 ) 2 pale yellow todorokite MnO 4 black calcite CaCO 3 white dolomite CaMg(CO 3 ) 2 white gypsum CaSO 4× 2H 2 O very pale brown quartz SiO 2 light gray humus Humus is not a mineral but it influences soil color, especially in the upper horizons. Humus is organic material that forms in a soil when living organisms decay. black 2. What colors are commonly seen when iron (Fe) is present in the parent material of a soil? (0.25 pts) What color is commonly seen when calcium (Ca) is present in the parent material of a soil? (0.25 pts) Soil texture refers to the sizes of the mineral materials in a soil. All soils can be classified by the amount of sand (<2 to 0.05 millimeters), silt (0.05 to 0.002 millimeters), and clay (<0.002 millimeters) found in them. The soil texture triangle provides the names to classify soils with varying percentages of sand (bottom side of triangle), silt (right side of triangle), and clay (left side of triangle. The colors commonly seen when iron (Fe) is present is yellow or red. The colors commonly seen when calcium (Ca) is present is white.
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help