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Earth Science Exam 3
water and weathering
| Term | Definition | |||
|---|---|---|---|---|
| mechanical weathering | disintegration of rocks rocks break up into smaller pieces | can occur without air/water, happens on mars and moon | creates regolith | |
| frost wedging | splitting or break-up of rock by the pressure of water freezing in cracks, crevices, pores, joints or bedding planes. | |||
| thermal expansion | extreme temperature may break up rocks in deserts | |||
| chemical weathering | decomposition of rocks minerals within rocks break into chemical components and may form soil necessary for soil formation | needs water to function warm and humid climates have a faster rate of weathering than dry climates | ||
| mass wasting | movement of material down a slope due to pull of gravity | makes valleys grow wider over time and is major factor in landscape evolution | leading cause of property damage in the United States | |
| Types of mass wasting | falls, slides. flows | |||
| falls | movement of individual pieces (sand, grain, boulders, etc.) | problems near steep slopes, such as cliffs causing rockfalls and debris fall | ||
| slides | movement of large amounts of material as a unified mass | occur in many areas at variable rates and scales, small to large. somewhat cohesive, controlling/delaying slide is possible | occur where slopes are common | |
| flows | movement of large amounts of material as a fluid or chaotic mass | |||
| slump | movement near lakes and rivers often aided by erosion by water along steep banks | |||
| rockslides | massive movement in mountains often triggered by earthquakes, heavy rain or snowmelt | |||
| mass wasting | flows are most widespread form of mass wasting | do more economic damage in the united states than all other mass wasting processes combined | over a range of velocities | |
| erosion-transportation | rivers are responsible can occur by itself | combined with mass wasting, creates canyons and level landscapes | happens more quickly in areas where weathering has weakened rocks | |
| wind erosion | in deserts, moving sand and silt | |||
| glacial erosion | dominant during last ice age, minor today | |||
| rivers | main cause of erosion | ability to erode is affected by velocity and material it flows over | ||
| river velocity influenced by | slope of the land discharge shape of channel base level | |||
| slope of the land | flows rapidly in hilly areas than flat terrain | |||
| discharge | rivers flow faster when more water is added | |||
| debris in the channel | slow overall velocity | |||
| shape of channel | water slows in narrow or shallow channels | |||
| base level | elevation of ocean, lake, reservoir, etc. that a river flows into. Rivers erode landscape down to this point | |||
| changing base level | if a river's base level is lowered, the river's velocity will increase, ti will erode it's channel deeper, possibly forming a canyon | if base level is raised, river's velocity will decrease, it will begin to deposit sediment in it's channel | ||
| river sediment | when a river's velocity falls, it deposits sediment | |||
| deltas | sand, sitl and that form at the mouths of rivers | |||
| alluvial fans | similar to deltas, forming on dry land | |||
| levees | accumulations of sand and gravel form along the banks of a river. | well developed levees may be high enough to reduce the number of small floods | ||
| river change with time | effects of erosion and mass wasting mass wasting causes valleys to widen with time | rivers erode valleys deeper until base level landscape is leveled off, surrounding elevations become close to sea level | ||
| rivers and floods | all rivers flood, not in the same way | |||
| mountain rivers | flash floods, moves large material (boulders), water stays within channels | rivers prone to flash floods sometimes are partially controlled by dams | ||
| rivers in flatter terrains | overflow their banks, more widespread flooding, difficult to control | |||
| floods in china | long history of major floods along two of its main rivers - yangtee and yellow river | problem with flood control on yellow river is terrain rivers flow over a flat surface, floods often, changes course frequently | yangtee causes massive floods, now partially contained and controlled by gorges dam | |
| flood control | floor plans are protected by artificial levee or flood walls | protect from 100-year flood | ||
| 100 year flood | statistical chance of flood occurring once a century | |||
| flood probability | 100 year flood occurs about every 100 years | has 1% chance of happening in a given year | ||
| groundwater | 14% of world's fresh water, remaining is frozen in glaciers | 95% of liquid, fresh water is groundwater contained in sediment, soil, and rock. Rivers and lakes hold most of the rest | for groundwater to accumulate, sediment and/or rocks must be able to hold water and transmit it | |
| The Water Table | top of groundwater follows land surface. highest under hills lowest under valleys | groundwater may flow back to the surface at low spots or sides of hills | ||
| two significant properties | porosity and permeability | |||
| porosity | rocks must have open spaces in order to store groundwater. | most sediment is porous, sedimentary rocks are too | ||
| permeability | rocks act like sponges, allowing water to pass | sedimentary rocks (not shale) are permeable | ||
| aquifers | materials with high porosity and high permeability that let water pass through easily | sand, gravel, sandstone, conglomerate. limestone | ||
| aquitards | materials with low permeability that slow or block water flow | clay, shale, ingenuous and metamorphic rocks | ||
| caves | form where groundwater can remove large amounts of rocks | can form in many different rocks, limestone contains largest caves | area with substantial cave development and sinkholes has karst topography | |
| geothermal activity | areas where groundwater is heated by magma, hot springs may form | if hot groundwater is trapped, geysers may develop | ||
| wetlands | areas that may be covered by water all year or few weeks groundwater is significant | depth ranges up to six feet | most biologically diverse | connected to hydraulic cycle by groundwater, rainfall, and rivers |
| hydrology | area that is flooded or subsurface is saturated for significant amount of time during growing season | |||
| hydrophytic vegetation | restricted variety of plants will grow there (cattails, reeds) due to low oxygen, nitrogen, and nutrients in the soil | |||
| hydric soils | soils waterlogged and anoxic. smells sulfuric | |||
| why wetlands are drained? | great ecosystem, not good for humans biting insects poison sumac not great for construction | |||
| importance of wetlands | water purification flood control habitat recreation and ecotourism | |||
| water purification | water hyacinths and duckweed, consume sewage and remove heavy metal toxins from water | Kolkata, India, sewage treated by 48 mile wetland | ||
| flood control | act as natural storage reservoirs for excess rainwater, reducing flooding in nearby areas | |||
| habitat | nesting sites for many types of birds and home to large numbers of endangered species | |||
| recreation and ecotourism | everglades in florida | |||
| types of wetlands | bog, fen, marsh, swamp | |||
| bog | acidic water (pH > 7), receives much water from rainfall | |||
| fen | alkaline (pH < 7) receives much water from groundwater filtered through limestone | |||
| marsh | open, shallow, dominated by grass, reeds, etc. biodiversity is low | |||
| swamp | wetland with deeper water, dominated by trees and shrub. wet all year-round |
Created by:
sandir04
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