Geo Review2 - Geo Study 1 What is mechanical weathering...

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Geo Study 1) What is mechanical weathering? Chemical weathering? Hydrolysis? Breaks intact rock into chunks of debris. Ranging in size boulders 256 mm+ cobbles 64 to 256 mm pebbles 2 to 64 mm sand 1/16 to 2 mm silt 1/256 to 1/16 mud less than 1/256 mm Chemical weathering refers to the chemical reactions that alter or destroy minerals when rock comes in contact with water solutions or air. Chemical weathering takes place much faster in the tropics than in deserts or near poles because reactions take place more quickly in warm, wet conditions. Dissolution: when minerals dissolve into water. Primarily affects salts and carbonate minerals, quartz dissolves slightly. Organic chemical weathering – roots of plants, fungi, and lichens secrete organic acids that help dissolve minerals in rocks. During hydrolysis, water chemically reacts with minerals and breaks them down. Works faster in slightly acidic water. Hydrolysis breaks down silicate minerals such as feldspar, amphibole, pyroxene, mica, and olvine and transforms them into types of clay. Fastest weathering / Least stable Halite Calcite Olivine Ca-Plagioclase Pyroxene Amphibole Biotite Orthoclase Muscovite Clay Quartz Gibbsite Hematite Slowest weathering / Most stable Mafic minerals weather by oxidation, felsic minerals by hydrolysis, carbonates and salts by dissolution. Oxide minerals don’t weather at all. 2) What happens to iron as mafic silicate minerals weather? See above! 3) What are the final end products of the complete weathering of all silicate minerals? Quartz! 4) What are the three types of clastic sedimentary particles? They are defined by grain size, but do they have characteristic grain shapes as well? How do their grain shapes affect their transport, sorting, and deposition?
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Gravel, sand, & clay. o Varies from Angular to well rounded and from poorly sorted to well sorted. o The farther a particle is transported, the more rounded and better sorted it becomes. Becomes more mature. 5) What is traction and which sedimentary particles are transported in this way? Saltation? Suspension? Traction is the movement of larger particles along (dragging) the bed of a stream or river body. At any given velocity, particles beyond a critical mass will remain stationary. Below that will move by traction, below that by saltation, and the smallest by suspension. 6) What is the importance of the cohesive character of clay to the erosion of mud deposits? Mud sized particles are tabular so they are sticky. To pick up mud particles it takes a greater current velocity than expected. Once in suspension, however, it takes a lot less to keep them moving. 7) What are the extrabasinal sedimentary rocks and which are the intrabasinal? What does it mean to be intrabasinal? Depositional basin - a place where sediments accumulate
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Geo Review2 - Geo Study 1 What is mechanical weathering...

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