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32 Cards in this Set
- Front
- Back
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When does weathering occur?
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when ever it wants to
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Difference between weathering and erosion
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Weather is the act of decomposing and breaking down rocks. Erosion is the movement of weathered material.
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difference between physical and chemical weathering
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Breakdown of rack into smaller pieces with no change in chemical composition. Chemical - the breakdown of rocks by chemical agents
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what environmental factor has the greatest control on weathering? When does physical weathering dominate? Chemical weathering?
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Physical weathering dominates is water-limited environments( air, cold, high elevations). influenced by rock mineralogy, zones of weakness, promotes chemical weathering by increasing SA
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Ultimately, what drives most erosion?
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Gravity, but it usually works with a fluid, water or air.
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What are the 3 basic products of weathering?
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mechanical-sediment. chemical-clay. solution-dissolved salts
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What are examples of physical weathering? Exactly, how does each cause physical weathering?
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Thermal stress (expansion) Ice wedgins, biogenic(roots animal burrowing) abrasion, exfoliation, salt growth, wetting/drying, meterite impacts
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What are examples of biogenic physical and chemical weathering?
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Animals burrowing, and plant roots
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How does physical weathering occur with flowing water and air?
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Utilizes zones of weakness
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What is a ventifact?
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A rock that has been weathered by wind
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What attributes of rocks influence the type and rates of weathering?
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Surface Area, minerology,
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What is the role of fractures, joints and bedding planes in weathering?
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Those are points of weaknesses
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How does physical weathering promote chemical weathering?
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Increases SA
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With respect to grain morphology, where does chemical weathering occur?
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Surface
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What are the main products of chemical weathering?
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asdf
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What are the primary controls on rates of chemical weathering?
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Water abundance and climate
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What is the relative susceptibility to chemical weathering of the common minerals found at the Earth’s surface?
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Least susceptible
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What is the role of microbes in chemical weathering?
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increase chemical weathering. cement grains.
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What are the 3 basic chemical reactions that describe chemical weathering on Earth?
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Dissolution, Hydrolysis, Oxidation/reduction
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What is dissolution? What are the products? What minerals are most susceptible to this form of chemical weathering?
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dissolution of soluble minerals. How caves are created sometimes
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What is the chemical formula for carbonic acid? How is it formed?
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H2CO3. CO2 from the air is dissolved in rain water.
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What is the average pH of rain water?
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5.6
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What is the basic chemical process of hydrolysis? What minerals are most susceptible? Weathering product?
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Hydrolysis, Feldspar reacts with free hydrogen ions in water to form a secondary mineral.
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What is the most common mineral on the Earth’s surface?
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Feldspar
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What is reduction? What minerals are most susceptible?
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Is the addition of an electron. water saturated environments where oxygen demand is high. Iron
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What is oxidation? What minerals are most susceptible?
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Is the loss of an electron, typically forming oxides. Hematite, Goethite, gibbsite
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What are the weathering products of these common minerals: Quartz, Feldspar, Amphibole, Pyroxene, Biotite, Muscovite?
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quartz grains, clay minerals, limonite, hematite
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What happens to the solution phase (ions) of weathering?
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They are eroded away
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What is soil?
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surface material that forms due to weathering. include an organic component
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What are the controls on soil development?
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climate, topography, and precursor material
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What is the profile of a soil (i.e., layers)?
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top soil, soil leached, B-Horizon, little organic matter, C-horizon, bedrock cracked and weathered.
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How would you recognize a paleosol in the rock record?
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It would not exist in the current climate
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