what are the causes of weathering?
916047
It's not a complete list, but they're all causes.
704222
rain water is mildly acidic (carbonic acid) and so will dissolve minerals found in rock.  For example, if you look at an old building made from limestone the corners will be slightly round and the surface will be pitted.  This is because limestone is made from calcium carbonate which is easily dissolved by acids.\nThis is also the same effect which produces limstone caves and why the surface of rocks appear discoloured and weathered.
235878
Soils vary widely in composition and structure from place to place. Soils are formed through the weathering of rock and the breakdown of organic matter. Weathering is the action of wind, rain, ice, sunlight and biological processes on rocks, which breaks them down into small particles. The proportions of minerals and organic matter determine the structure and other characteristics of a particular soil.\n\nSoils can be divided into two general layers (strata): topsoil, the topmost layer, where most plant roots, microorganisms, and other animal life are located, and subsoil, which is deeper and often more dense and contains less organic matter.\n\nWater and air are also components of soils. Mineral and organic solids comprise about half of the soil by volume. Water occupies the spaces between soil particles and is held by surface tension on particle surfaces. Air occupies the remaining void space. Both water and air components of soils are important to plant growth and other life in the soil profile of a particular ecosystem.\n\nThe rock and mineral content of soils is categorized according to particle size, from sand (coarsest), to silt and clay (finest). The ratio of these particles to a great degree determines the soil classification and characteristics.\n\nSoils serve as habitats for soil organisms varying in size from microorganisms to small animals. The character of soils is intricately tied to bioturbation and the biochemical functions performed by soil organisms.\n\nFormer soils which become buried below the effects of organisms are called paleosols.\n\nSoils develops naturally over time through the action of plants, animals, and weathering. Soils are also affected by human habitation. People can alter soils to make them more suitable for plant growth through the addition of organic materials and natural or synthetic fertilizer, and by improving their drainage or water-retaining capacity. Human actions also can degrade soils through the depletion of nutrients, pollution, contamination, and compaction, and by increasing the rate of erosion, which is the relocation of soil through the movement of water or wind.
292725
I will give this question a stab and I caution that the answer may not be exactly correct. \n\n The weathering complex refers to the action of wind and rain on sculping the geography of the Earth or any other planet for that matter. The Grand Canyon is a prime example of this action. It was sculped--there is probably a better word to use here but I can't think of it--by the flow of the Colorado River. In this particular area of the country where it does not rain very frequently and there is sparce vegitation, when it does rain hard, the erosion can be severe. The same can be said of soil erosion caused by the wind. During the 1930's the mid-west became a dust bowl and millions of tons of soil were displaced by wind.  In some places when the wind blew, it was like night at mid day because of all the dusk in the air.  \n\nIf you have ever driven through the Appalachian Mountians and looked at where the road was cut through the mountians you would have noticed that the layers of sedamentary rock seemed to abrutly  terminate at one side of the mountain. It is like a giant hand came down and scooped out part of the mountain. That giant hand was the stream or river at the bottom of the mountain. It literally cut through the mountain during millions and millions of years. \n\nOne of the best examples of wind erosion in the U S can be found at Great Sand Dunes National Monument in southern Colorado.  There there are sand dunes hundreds of feet high cause by the wind carrying the particals of sand into that sheltered area. A lesser example of this are the sand dunes in Dunes State Park in Indiana along the south shore of Lake Michigan. And of course everyone has seen the sand dunes of the Sahara Desert in the movies.
69910
If you are asking what are the minerals that are most resistant to weathering, I can give you some help. How fast any particular mineral actually moves through the rock cycle is hard to answer, since it really depends on the setting.  In general the deeper a mineral forms (higher pressure and temperature) the more unstable it is at the surface. Quartz and muscovite are two of the more stable minerals. \n\nHere's some chemical weathering rates:\nMean lifetime of 1 mm or fresh rock (Nahon, 1991)\nRock Type................ Climate..................... Lifetime (years) \nAcid rocks...............tropical semi-arid.......... 65 to 200\n..................................tropical humid........................ 20 to 70\n..................................temperate humid........................ 41 to 250\n.................................. cold humid.................... 35 \nMetamorphic rocks..... temperate humid..........33 \nBasic rocks.................... temperate humid.........68\n..........................................tropical humid.............. 40
460042
Dust and sand is picked up from the soil as the wind passes over it.  It's more common to pick up dust and sand when:\n1) it's a deforested area with easy 'soil access' like a desert or plains (it doesn't happen in forests, or on grasslands);\n2) the soil exposed is dusty, sandy, or contains many small particles which can become windborne (it doesn't pick up gravel, or mud);\n3) the wind speed is high.\n\nI don't know exactly about 'abrasion' and 'weathering'.  in common usage, I'd say 'weathering' is ther main category which refers to changes in an object's surface in response to exposure.  Wethering can be caused by UV exposure (sunlight), acid rain, etc etc.  Abrasion is only caused by physical rubbing across things: sandstorms, rivers, etc.  Abrasion is IMHO a subset of weathering.
270375
It depends on a lot of things. Among them, you should consider the amount of erosion, presence of water, wind, all those weathering factors that could impact the rate at which dirt (I'm guessing) accumulates.
478862
Abrasion by wind-driven sand.\nParticle removal by wind alone.\nDecomposition and weakening due to sunlight (especially the UV).\nCracking due to temperature changes.\nThis doesn't include biological damage which can be severe due to chemicals secreted by various growths such as lichen.
307714
because weathering breaks down rocks     in time it will bring down mountains      weatheing makes streams    plants use stream water    weathering makes rivers   and if not makes them it makes them bigger wich makes water more conveinient   and in old times rivers were the main and/or only way for travel to great distances and trade.    and thats just a tiny little detail me brother 11 yr old brother just thought of
410825
Others have had similar problems and solved them.  See the link.  In general, metals (especially iron and its alloys) rust when exposed to moisture in the presence of oxygen.  The rust is a loose collection of molecules that allow more moisture and oxygen to reach the base metal.  For example, you can shine aluminum but it will quickly dull with oxidation.  The aluminum corrosion however forms a tenacious film that protect the metal from additional corrosion.  I heard that copper (flashing?) on a rooftop can cause aluminum gutters to corode.  Various alloys of iron (steel) including heat treatments may impart various corrosion properties, however, chrome is usually added to form stainless steels that best resists rusting.  Silicon steel may have to be protected.  Good luck.
1145145
Dissolved materials that can precipitate out of solution can cause problems with appliances. They are a particular problem with systems that heat water, because this increases precipitation and causes scale. This can reduce efficiency of heating elements, and can block pipes.\n\nHeating systems suffer less, because it is always the same water, so once the solids have deposited out there are no more to add to the scale, and this is very little scale. However, other dissolved materials can cause problems by leading to corrosion.
193598
well, there is the theory of plate tectonics which tells us that the earth's crust is comprised of plates that converge, spread, subduct,  and slide with one another.  This is the main culprit of orogeny, which is mountain building.  Then you have to consider weathering which is performed mainly by wind and water, ie..rivers, lakes, streams, ocean currents and tides.  Once that has taken place erosion takes effect and carries the weathered material away and deposits it somewhere else.
211211
You need to think about this in terms of the question, that is what one of these processes involves movement of sediment.\n\nWeathering does involve movement of sediment, since weathering includes lots of processes that break down rocks into smaller particles or even dissolve rocks. Dissolution of limestone by carbonic acid in water is weathering that 'moves' rock. Freeze-thaw weathering of sandstone breaks the sandstone into smaller particles that are carried away by water, gravity, and wind. \n\nDeposition is the end result of the process of moving sediment, and may be the only one that does not answer your question, but because it is part of the process of 'moving' sediment it probably counts. \n\nErosion definitely moves sediment. Soil, sand, and rock are eroded by moving water and transported to new locations. \n\nAbrasion results in 'moving' sediment. Glaciers abrade underlying rock and grind it into small particles. Wind blows sand grains against rock and abrades it and reduces it to smaller particles. \n\nI think the only correct answer here is "all of the above.”
93104
acid deposition, form of precipitation (rain, snow, sleet, or hail) containing high levels of sulfuric or nitric acids (pH below 5.5—5.6). Produced when sulfur dioxide and various nitrogen oxides combine with atmospheric moisture, acid rain can contaminate drinking water, damage vegetation and aquatic life, and erode buildings and monuments. Automobile exhausts and the burning of high-sulfur industrial fuels are thought to be the main causes, but natural sources, such as volcanic gases and forest fires, may also be significant. It has been an increasingly serious problem since the 1950s, particularly in the NE United States, Canada, and W Europe, especially Scandinavia.
672632
i don't know exactly how it works but rust is caused by oxidisation, which is a reaction between oxygen and the metal. i'm not sure why, but water speeds up the process, allowing the oxygen in. but water does not cause rust. oxygen does.
1089980
Water\n\nSplash erosion is the detachment and airborne movement of small soil particles caused by the impact of raindrops on soil. Sheet erosion is the result of heavy rain on bare soil where water flows as a sheet down any gradient, carrying soil particles. Where precipitation rates exceed soil infiltration rates, runoff occurs. Surface runoff turbulence can often cause more erosion than the initial raindrop impact. Gully erosion results where water flows along a linear depression eroding a trench or gully.\n\nValley or stream erosion occurs with continued water flow along a linear feature. The erosion is both downward, deepening the valley, and headward, extending the valley into the hillside. In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is relatively steep. When some base level is reached the erosive activity switches to lateral erosion which widens the valley floor and creates a narrow floodplain. The stream gradient becomes nearly flat and lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion by far the most erosion occurs during times of flood, when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes, suspended abrasive particles, pebbles and boulders can also act erosively, as they traverse a surface.\n\nWind\n\nWind erosion, also known as eolian erosion is the movement of rock and/or sediment by the wind. Windbreaks are often planted by farmers to reduce wind erosion. This includes the planting of trees, shrubs, or other vegetation, usually perpendicular or nearly so to the principal wind direction. The wind causes dust particles to be lifted and therefore moved to another region. Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation. An example is the formation of sand dunes, on a beach or in a desert.\n\nGlacial\n\nIce erosion is caused by movement of ice, typically as glaciers. Glaciers can scrape down a slope and break up rock and then transport it, leaving moraines, drumlins and glacial erratics in their wake, typically at the terminus or during glacier retreat. Ice wedging is the weathering process in which water trapped in tiny rock cracks freezes and expands, breaking the rock. This can lead to gravity erosion on steep slopes. The scree which forms at the bottom of a steep mountainside is mostly formed from pieces of rock broken away by this means. It is a common engineering problem, wherever rock cliffs are alongside roads, because morning thaws can drop hazardous rock pieces onto the road.
518090
What you are observing is the oxidation and weathering of a rock. The outside of the rock is exposed to the elements and gets bleached out, the inside is protected by the outer layers.