1a. With equations, explain (1) Oxidation and (il) Dehvaration
b. How does (1) rock type (ii) slope (iii) climate influence weathering?
c. Explair how (i) geological factor and (ii) over grazing cause erosion
a. (i) Oxidation: Oxidation is a chemical reaction where a substance loses electrons. In the context of weathering, it refers to the process where a mineral or rock reacts with oxygen in the presence of water or air, leading to the formation of new minerals or the breakdown of existing ones. This process usually results in the reddish or brownish coloration often observed in weathered rocks.
(ii) Dehydration: Dehydration, in the context of weathering, refers to the removal of water or the loss of water molecules from a substance. This process can occur when certain minerals react with the atmosphere, causing them to lose water and undergo changes in their structure and properties.
b. (i) Rock type: The type of rock influences weathering because different rocks have varying levels of resistance to weathering processes. For example, soft and porous rocks, such as sandstone, are more susceptible to weathering as compared to hard and dense rocks, such as granite. The mineral composition of the rocks also plays a role, as some minerals are more prone to chemical reactions with water and air, leading to faster weathering.
(ii) Slope: Slope influences weathering because it affects the movement and accumulation of water and the exposure to wind. Steep slopes tend to experience faster rates of weathering as water runoff and wind can erode the surface more intensively. Additionally, gravity plays a role in downslope movement, leading to increased erosion and transport of weathered material in steeper areas.
(iii) Climate: Climate influences weathering as temperature, precipitation, and freeze-thaw cycles can enhance or inhibit different weathering processes. In warm and humid climates, chemical weathering tends to dominate, as moisture and heat promote the breakdown of minerals. In cold climates, freeze-thaw cycles can lead to mechanical weathering, where water trapped in cracks freezes and expands, causing the rocks to crack and break apart.
c. (i) Geological factors: Geological factors such as the presence of fault lines, fractures, and joints in rocks can contribute to erosion. These features provide avenues for water to infiltrate and accelerate weathering processes. The presence of inclined layers or weak rock formations can also contribute to erosion, as these layers are more susceptible to erosion than other layers.
(ii) Overgrazing: Overgrazing, which occurs when there are too many grazing animals for the available vegetation, can cause erosion. Excessive grazing removes the protective plant cover, exposing the soil to the erosive forces of wind and water. Without vegetation to hold the soil in place, it becomes more prone to erosion and can lead to the formation of gullies and loss of fertile topsoil. Additionally, the trampling of animals can further compact the soil, reducing its ability to absorb water and increasing surface runoff.