Geography
Explain the following terms:
(a) Exfoliation
(b) Hydration
(c) Weathering
(d) Rocks
(e) Minerals
(f) Denudation
(g) Mechanical weathering
Weathering
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Answer
(a) Exfoliation — The changes in temperature during summer and winter and in case of arid region, during day and night, cause expansion and contraction in the rock surfaces. This causes the rocks to break-up or peel off. Rectangular rock blocks are thus, gradually rounded by splitting away of sharp corners. This process is called exfoliation.
(b) Hydration — Hydration is the chemical reaction of water with minerals present in rocks. It changes the proportion and composition of rocks and minerals. It weakens the rocks and ultimately the rock breaks-up.
(c) Weathering — Weathering is described as the breaking down or dissolving of rocks and minerals on the surface of the earth. Water, ice, acids, salts, plants, animals and changes in temperature are all agents of weathering. It is a static process and leads to the formation of soil.
(d) Rocks — Rocks are aggregates of minerals and have no definite chemical composition. Rocks makeup most of the solid materials of the lithosphere. On the basis of their formation rocks are classified into three types:
- Igneous rocks
- Sedimentary rocks
- Metamorphic rocks.
(e) Minerals — A mineral is a naturally occurring, homogenous solid that has definite chemical composition with its own chemical and physical properties, e.g., silicates and quartz.
(f) Denudation — Denudation is a dynamic process that includes the disintegration and decomposition of rocks, transportation of the eroded material and deposition of it at some other place. Therefore, process of denudation is two-fold process that is both destructive and constructive.
(g) Mechanical weathering — Mechanical weathering is responsible for the disintegration of rocks by the elements of weather such as heat, frost and wind. Mechanical weathering does not change the composition of rocks. It depends on the following factors:
- Extremes of temperature
- Nature of rocks
- Structure of rocks
- Frost
- Wind
- Slope of lands
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Related Questions
Fill in the blanks:
(a) Weathering is the …………… of rocks by agents like temperature, rain, etc.
(b) Erosion is the …………… of rocks by running water.
(c) Mechanical weathering is …………… of rocks by elements of weather such as heat, frost, wind, etc.
(d) Carbonation is the reaction of …………… acid on minerals.
(e) B-Horizon of soil profile contains …………… .
Answer the following in one word:
(a) Disintegration and decomposition of rocks.
(b) A process which wears down the rocks.
(c) The breaking up of exposed rocks due to change in temperature, frost, plants, and winds.
(d) Unequal heating causes expansion in rocks resulting in breakdown of rocks.
Differentiate between chemical and mechanical weathering
Differentiate between weathering and denudation