(a) What is weathering ?
(b) Enumerate three processes involved in rock weathering
(c) List and discuss briefly the agents of two of these processes
Explanation
(a) Rock weathering is defined as the process whereby rocks are broken down into tiny pieces to form the soil.
(b) Three processes involved in rock weathering are: (i) Physical weathering/process (ii) Biological weathering/process (iii) Chemical weathering/process
(c) Agents of rock wethering are;
- Water: causes hydration of rocks and minerals.
- Gravity: an agent of physical weathering and causes abrasion.
- ice: in cold regions, ice formation and subsequent thawing, changes the gap size between rock fragments, loosens them and causes weathering.
- acids: acid attack is a common cause of weathering. carbonic acid and sulfuric acid are commonly implicated as agents of chemical weathering.
- salts: crystal formation of salts in the gaps and fissures also causes weathering of rocks.
- winds: can shape and move loose fragments, thus progressively weathering the rocks.
- plants: grow into crack and fissures. The expanding roots, uptake of chemicals and release of chemicals into rocks causes weathering.
- animals: burrow animals break down rocks, other animals use other means to cause weathering.
- temperature changes: heating and cooling enhances weathering.
- pressure changes
- gases: such as carbon dioxide, oxygen, sulfur oxide, etc. causes acidification or oxidation of rocks.
- microorganisms: break down, acidify and chemically attack soil and rocks and causes weathering.