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Asked by sapowapo - 6 years ago
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Richard Level 78 / Retired Dentist
Answered 6 years ago
Weathering takes place anywhere that water and/or air can penetrate. It produces altered material that is more stable at the Earth's surface than the original parental material, and provides the material that becomes soil or sedimentary rock. The driving forces for weathering are:

1. Solar energy - causes circulation of the atmosphere (weather) and determines climate and vegetation.
2. Earth's internal energy - forces within the Earth uplift deeply buried rock and expose it to weathering.

Two types of weathering are recognized:

A. Mechanical Weathering
B. Chemical Weathering

The rate of weathering is controlled by:

* Surface Area (Related to particle size) controls weathering because the smaller the particle size, the larger the surface area exposed to weathering for a given volume of material. The presence of joints therefore increases a rock's surface area. Spheroidal weathering, which produces rounded surfaces on weathered rock, can be caused where:

1. Concentric shells of altered rock material (clay), produced by chemical weathering, are easily removed.
2. Faster weathering of edges and corners of rock tends to produce rounded surfaces, where a sphere has the least volume to surface area ratio of any geometric form.
* Climate controls weathering in that rocks experience the most thorough and rapid chemical weathering in warm, humid climates. Weathering rates are lowest in desert and cold climates.
* Parent Material (mineral composition of rock) controls weathering processes because minerals that fonn at high temperature and high pressure are less stable at the Earth's surface than low temperature, low pressure minerals. Bowen's Reaction Series can be used in reverse to predict the ease of chemical weathering of common igneous minerals.
* Presence of Plants and Animals influence weathering as chemical and physical weathering rates are increased by the action of plants and animals.
* Topography affects weathering as irregular, steep topography exposes more rock to weathering than horizontal surfaces.
mikester123 Level 14
Answered 6 years ago
Weather mainly and river conditions etc
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