Chapter 5 - Weathering

Chapter 5 - Weathering - Chapter 5 Review (Bold print...

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Chapter 5 Review (Bold print indicates potential quiz question) (1) External processes include (1) weathering—the disintegration (physical breakdown) and decomposition (chemical alteration) of rock at or near Earth's surface; (2) mass wasting—the transfer of rock material and soil downslope under the influence of gravity; and (3) erosion—the physical removal of materi al by a mobile agent, usually water, wind, or ice. They are called external processes because they occur at or near Earth's surface and are powered by energy from the Sun. By contrast, internal processes, such as volcanism and mountain building, derive their energy from Earth's interior. Two types of weathering: mechanical and chemical (2) Mechanical weathering is the physical breaking up of rock into smaller pieces. Rocks can be broken into smaller frag ments by frost wedging (where water works its way into cracks or voids in rock and upon freezing, expands and enlarges the openings), unloading (expansion and breaking due to a great reduction in pressure when the overlying rock is eroded away), and biological activity (by humans, burrowing animals, plant roots, etc.). (3) Chemical weathering alters a rock's chemistry, changing it into different substances. Water is by far the most impor tant agent of chemical weathering. Oxygen dissolved in water will oxidize iron-rich minerals, while
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This note was uploaded on 03/30/2011 for the course GEOL 101 taught by Professor Galland during the Fall '08 term at BYU.

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Chapter 5 - Weathering - Chapter 5 Review (Bold print...

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