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35 Cards in this Set
- Front
- Back
types of weathering
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physical, chemical
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physical weathering
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-breakup of massive rock (bedrock) into small particles through the action of physical forces acting at or near Earth's surface
-produces regolith -disintegrates rock mechanically without altering chemical features - frost action, salt-crystal growth, unloading (exfoliation) |
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chemical weathering
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- chemical change in rock-forming minerals through exposure to atmospheric conditions in the presence of water
- decays rock by chemical reactions - oxidation, hydrolysis, acid action |
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causes of physical weathering
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daily heating and cooling of rock surface, wedging of the rock by growing plant roots
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controlling factors of chemical weathering
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water, temperature
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frost action
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- rock breakup by forces accompanying the freezing of water
- caused by the repeated growth and melting of ice crystals in rock fractures (joints) |
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salt-crystal growth
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-a form of weathering in which rock is disintegrated by the expansive pressure of growing salt-crystals during dry weather periods when evaporation is rapid
-caused by the growth of salt crystals in rock pores in arid dry climates - breaks individual grains of rock free, and creates landforms such as niches and arches. It can also damage brick and concrete |
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unloading (exfoliation)
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-caused by the removal of weight, rock expansion and the formation of sheeting structure
-unloading of the weight of overlying rock layers can cause some types of rock to expand and break loose into thick shells |
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oxidation
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- chemical union of free oxygen with metallic elements in minerals
- oxygen dissolved in water chemically reacts with minerals and forms oxides (iron rust) |
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hydrolysis
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- chemical union of water molecules with minerals to form different, more stable mineral compounds
- granular disintegration of crystal rock structure by water |
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acid action
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carbon dioxide dissolved in water produces carbonic acid which disintegrates some minerals (limestone, marble)
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major external forces responsible for creation of landforms
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running water, wind, waves, glacial ice
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stream carrying capacity
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the ability to carry stream load, increases greatly as velocity increases in times of flood
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general energy balance of a stream flow
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95% overcoming external and internal friction in the channel in a unit of time
5% causing erosion and moving load |
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major forms of stream erosion
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hydraulic action, stream abrasion, corrosion
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hydraulic action
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stream erosion by the force of flowing water against stream sides and bed
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stream abrasion
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material being carried in stream roll and bounce off the bed and walls and break off other material
- erosion of bedrock of a stream channel by impact of particles carrid in a stream and by rolling of larger rock fragments over the streambed |
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corrosion
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chemical processes of weathering in a stream
- erosion of bedrock of a stream channel by chemical reactions between solutions in stream water and mineral surfaces |
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how do alluvial terraces form
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form when an aggrading river loses its sediment input and begins degrading it's bed, leaving terraces behind as it cuts deeper into its sediment filed valley
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processes of wind erosion
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deflation, abrasion
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deflation
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the process of lifting and transporting loose particles of soil and regolith in turbulent suspension from dry surfaces by wind
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wind abrasion
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the process of bedrock erosion caused by solid particles carried by wind
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landforms made by wind deposition
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dunes, loess
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glacier
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body of ice that forms when ice becomes too thick, then its lower layers become plastic, ice mass begins to move and a glacier forms
2 forms: alpine glaciers, continental ice sheets |
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major landforms deposited by glaciers
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stratified drift, till, moraines, drumlins
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major landforms made by deposits of glacial melt water
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outwash plain, kettle, esker, delta kame
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runoff
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the flow of water from continents to oceans by way of stream flow and ground water flow
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runoff intensity is defined by:
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amount of precipitation, rate of evaporation, permeability of surface rock and the soil, vegetation density, angle of slope
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subsystems of a stream system
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catchment system, transport system, depositional system
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fluvial process
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work of the stream, consists of 3 processes: erosion, transportation, deposition
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ways of stream transportation
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-in solution (e.g. CaC03 from limestone)
-in suspension (the finest solid particles) -by saltation (mechanical transport of large solids) |
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ablation
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the loss of ice and snow by evaporation and melting
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forms of wind erosion
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delation hollows, dust storms
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deposition
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occurs if stream load is greater than stream capacity
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stream flow (discharge)
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volume of water flowing past a cross section of channel in a unit of time (m3 per second)
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