Ch 10 hw - chemical weathering occurs when air and water...

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Crystal Cozart ESC1000 September 20, 2009 Ch. 10 Homework 1.) The processes that decompose rocks and convert them to loose gravel, sand, clay, and soil are called weathering . Loose soil and other weathered material offer little resistance to rain or wind and are easily eroded. Thus erosion processes soon pick up and carry off weathered rocks and minerals. Agents may then transport the weathered material great distances and finally deposit it as layers of sediment on Earth’s surface. The laying down of rock-forming materials by any natural agent is called deposition . Transport is the movement of sediment by flowing water, ice, wind, or gravity. Weathering, erosion, transport, and deposition typically occur in an orderly sequence. 2.) Mechanical weathering (also called physical weathering) reduces solid rock to small fragments but does not alter the chemical composition of rocks and minerals. In contrast,
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Unformatted text preview: chemical weathering occurs when air and water chemically react with rock to alter its composition and mineral content. 3.) Five processes cause mechanical weathering: pressure-release fracturing, frost wedging, abrasion, organic activity, and thermal expansion and contraction. 4.) A talus is an accumulation of loose, angular rocks at the base of a cliff from which they have been cleared by mass wasting. Water expands by 7 to 8 percent when it freezes. If water accumulates in a crack and then freezes, the ice expands in a process called frost wedging. Ice pushes the rock apart but at the same time cements is together. When the ice melts, rock fragments tumble from a steep cliff. Rocks fell from the cliffs mainly as a result of frost wedging. 5.) The most important processes of chemical weathering are dissolution, hydrolysis, and oxidation....
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