Soil Forming Processes Flashcards
What is soil?
-the entire profile of weathered rock and unconsolidated rock material of whatever origin, lying above unaltered bedrock
What is illuviation?
When particles are accumulated/deposited
What is eluviation?
When particles held in suspension are removed (washed away)
What is translocation?
Movement of dissolved materials from one horizon of the soil to another
What is leaching?
Complete removal of soluble components of soil column
What is laterization?
Occurs in humid tropics, where there is movement of large amounts of water (results in eluviation and leaching). Forms laterites
What is calcification?
Occurs in areas where evapotranspiration exceed precipitation. Results in dry upward movement of alkaline soils hence calcretes are formed.
What is salinisation?
A more intense version of calcification
How does laterization occur?
O-horizon: no O-horizon as the decayed matter is used up by vegetation + decomposed into humus very quickly due to the high temperatures in the humid tropics -> forms humus in the A horizon
A-horizon: thin a-horizon, due to the humus being quickly used up by plants in the form of fertile soil. With the abundance of moisture in the humid tropics, leaching will occur -> the minerals from the a-horizon will be eluviated and translocated to the B horizon, resulting in a thicker B-horizon.
B-horizon: thick B-horizon, aka the zone of illuviation -> due to the minerals and particles from a-horizon such as clay, which were held in suspension are deposited in the b-horizon. Accumulation of oxides minerals are iron-rich rocks known as laterite. B horizon will tend to be reddish in colour due to the laterites
C-horizon: thick c-horizon. In the tropics, there is the presence of high rainfall -> there is the occurrence of deep chemical weathering at a deep depth due to increased percolation leading to an increased amount of saprolite and regolith in the C-horizon. Thus, this results in a thick c-horizon
