GEOG 2300: FINAL EXAM
185 Cards in this Set
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Floods
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when a stream overflows its channel
low lying ground next to the river (floodplain) is said to be inundated.
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Discharge and Flood Waves
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the discharge of a stream is a combination of base flow and surface flow
base flow is steady, year round flow from groundwater into the stream.
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What makes a big flood?
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numerous snow storms
saturated soils
flat terrain
large catchment
decimated fargo ND and grand folks
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Lakes
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receive input from streams, overland flow and groundwater
tend to be short lived (filed in by vegetation or dry out as outlet streams erode)
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Saline Lakes
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characteristic of arid areas (evaporation leaves salt behind)
excessive evaporation creates SALT FLATS
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Groundwater
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Precipitation absorbed by soil (infiltration)
If soil is saturated, or precipitation is too rapid - runoff (leading to overland flow)
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Zones of Subsurface water
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subsurface water saturating bedrock (saturation zone)
Water table marks upper boundary
above that is unsaturation zone
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Wells and Springs
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water table is highest under hills (seepage into streams lowers it in vallys)
Springs emerge where water emerges from the ground
can also dig or drill to the underground (wells)
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Aquifer
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porous rocks saturated with groundwater
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Aquiclude
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other layers of impermeable rocks keep water in the porous areas.
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unconfined aquifer
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when permeable sediments lie between the water table and the surface.
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confined aquifer
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if impervious rock caps the aquifer such that the pressure in the aquifer is higher than it would be without the impervious rock, then it is called this....
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Artesian Well
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A well dug into a confined aquifer is a...
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flowing artesian well
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If the pressure in the confined aquifer is great enough that water flows out of the well, the well is a...
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cone of depression
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when water is removed from an aquifer by a well, it pulls down the water table near the well, forming a....
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Aquifer Drawdown
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the amount by which the water level is reduced from the original water table level is called..
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pollutants in aquifers
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pollutants enter the groundwater from land fills, leaking oil tanks, surface pollutants infiltrating etc.\
once in pollutants go with the gradient toward a well or stream
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water problems in the U.S
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groundwater
aquifer depletion
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Urbanization Effects on water resources
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removing vegetation and constructing buildings
increases flooding potential
increases transport of pollutants
reduces water recharging aquifers
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Karst Landforms
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formed when water wears away rock
in landscapes made up of limestone and dolomite.
may lead to the excavation of caves.
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chemical weathering
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water ---> limestone + carbonic acid
calcium carbonate is a weaker rock
it is dissolved away (solution)
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Acid Action
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water can be acidic ex. carbon dioxide and water = carbonic acid
carbonic acid reacts with the carbonate minerals in rocks like limestone
occurs in soil and groundwater.
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water movement in karst areas
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surface streams
some streams also flow as underground drainage lines
surface streams can disappear into an underground channel
disappears to places such as: sink holes, soluble rock, caves
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sinkholes
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are solution depressions
rock ceiling collapses
dominate temperate karst landscapes
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Uvala
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where 2 or more sinkholes collapse together, it produces this large depression
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Karst Towers
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dominate tropical karst landscapes
towers are cone shaped, steep sided hills
sometimes referred to as haystack hills or eggbox
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Caves
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interior space in rock of significant size
in karst landscapes, these are produced by solution
weathering in rocks determine where water flows and where caves develop.
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Cave Features
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dissolved calcium carbonate is deposited on the walls
stalactites
stalagmites
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stalagmites
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calcium carbonate that rise up from the floor for these
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stalactites
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dissolved calcium carbonate that drips down from the ceiling to form an icicle like feature
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fluvial processes
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water flowing across the surface
includes overland and stream flow
features of land often shaped by water
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mechanical weathering
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wearing down of rocks
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what erosion, weathering, and deposition create
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creates erosional landforms
landforms make up landscapes
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Erosion
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Changes surfaces
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deposition
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leaves material behind
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Weathering
Mass movement
Erosion
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rocks are broken down
gravity moves debris
weathered debris is removed
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Weathering Types
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Physical
Chemical
Biological
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Physical Weathering
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imposed stresses breaks rocks apart
also referred to as mechanical
no chemical changes
frost action
thermal expansion
unloading
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Chemical Weathering
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alters chemical composition of the rock by making it weaker
some are resistant (quartz)
3 Types: hydrolysis, oxidation and carbonation
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Biological
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includes digging of animals, rooting in plants
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Joints (block separation)
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breaks in rock where there is no relative movement
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granular distegration
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if there are no joints, rocks may break up grain by grain
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Thermal Expansion
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different minerals expand and contract at different rates
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Unloading
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Overlying material is removed
pressures on underlying layers of rock lessen
Rocks exposed at the surface may break apart----definition of word
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Salt Wedging
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Growth of salt crystals in spaces in rocks
In arid regions, as water evaporates
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Hydrolysis
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if water is added, some minerals expand
altered version is softer and weaker
spheroidal weathering may result*
outer layers of rocks flake off *
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Oxidation
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minerals react with oxygen, iron, and aluminum oxidizes to produce a reddish color in soil.
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Acid Action
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water can be acidic
carbonic acid reacts with the carbonate minerals in rocks like limestone
occurs in humid area
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Biological Weathering
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influence of plants and animals, ex...plant roots, burrowing animals, influence humans
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Slopes
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Rocks are weathered below the soil as well as when exposed to the surface
resulting materials move down hill by mass wasting
covered by loose debris
material moves down due to gravity
subject to force greater than friction
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Angle of Repose
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maximum angle that loose material forming a slope can maintain without slipping
a balance between gravity and friction
solid rock can be 90 degrees
loose material can be 13 - 45 degrees
moisture usually increases
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Slope Erosion
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on slopes, overland flow picks up small particles
size depends on speed and volume of water flow and vegetation amount
typically the soil removed is replaced by added soil
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Accelerated Erosion
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rate of soil erosion may be increased by human activity
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Splash Erosion
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force of falling droplets of precipitation moves soil particles
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Unvegetated Slopes
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particles not held together by roots and surfaces of soil unprotected.
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Sediment Load
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amount of sediment removed by overland flow.
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Sheet Erosion and Rilling
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following splash erosion, overland flow layers of soil (definition)
in particular removes valuable topsoil.
on steep slopes may lead to RILL EROSION
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Colluvium
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when soil particles reach the base of the slope, they accumulate in a layer of debris
if it reaches a stream it will be washed away, and will add to debris at end of stream
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Alluvium
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any stream laid deposit from debris reaching the base of a slope and hitting a stream.
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Arid Environment
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normally sparse vegetation, impacted by grazing and fires.
erosion may progress quickly to create BADLANDS.
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Streams
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processes or Erosion, Transport, and Deposition
three phases of the same activity
we need to identify the processes and then the landforms they produce
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Processes of stream erosion
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hydraulic action
abrasion
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Hydraulic Action Stream Erosion
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water itself dislodges material
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Abrasion stream erosion
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Material carried by the river erodes the valley
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Corrosion stream erosion
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(least important) rocks and minerals dissolved by water.
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Stream Transportation of earth materials
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traction
saltation
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Traction
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sliding or rolling of particles
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Saltation
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water lifts particles off river bed - these particles bounce along
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Suspension
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fine sediment (clay and silt) suspended in the water
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Stream Capacity
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Streams therefore carry their loads in different ways
suspended loads are kept in suspension by turbulence
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Stream Gradation
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Originally, stream begin as a succession of lakes, falls and rapids
eventually the stream erodes to create a graded profile
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Graded Streams
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the first indication of gradation is the development of a flood plain
widens over time creating a flat valley floor
river meanders back and forth (ALLUVIAL MEANDERS)
on inside of bend - deposition
on outside of bend - erosion
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Landforms of Alluvial Systems
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when the alluvial meanders of a graded stream cut themselves off, an oxbow lake is formed
as alluvial streams migrate back and forth across a valley form, a flood plain is formed
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Meanders
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where uplift elevates a floodplain, a river will begin to cut down
this creates ENTRENCHED MEANDERS
do not move around like shallow meanders
however they may cut back to produce cutoff lakes.
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Alluvial Rivers and Floodplains
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thick floodplain accumulates which is prone to overbank flooding.
This FLOODPLAIN is bounded by steeply sloping BLUFFS
meanders in the floodplain erode to cut off bends
this may create an OX BOW LAKE
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Waterfalls
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waterfalls are an indication of an ungraded river profile
on major rivers tend to be the result of faulting
also created by glacial activity disrupting drainage patterns
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Wetlands
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are saturated at least some of the time so they can have low oxygen conditions (slows decomposition)
have high nutrient content, productivity and biodiversity
unique organisms, important for migrating birds
filters for pollutants
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Marshes
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are fresh, brackish, or saline with low herbaceous vegetation
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Swamps
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are wetlands with permanent, shallow water and woody vegetation.
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Estuary
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where freshwater and saltwater meet
highly variable environment
many fishes and shelfish spend larval stages here.
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Bogs
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(also muskeg) are acidic freshwater with few nutrients, composed largely of sphagnum, moss or lichens- fed by rainwater
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Fens
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are basic freshwater fed by groundwater (also composed of peat)
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Vernal Pools
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are seasonal wetlands that often act as breeding grounds for specialized animals
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Constructed Wetlands
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are designed to absorb flash floods, clean the water, provide habitat, or serve some other function
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Geographic Cycle
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Organizes fluvial landscapes according to a series of assigned stages
tectonic uplift creates steep mountain sides and rivers erode rapidly
this creates YOUTHFUL stage
subsequent erosion flattens the landscape to create peneplains
gradients of streams reduced (MATURE STAGE)
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The Global Ocean
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seas are smaller bodies of water, somewhat enclosed by land, exchanging water with oceans
some "seas" are actually large saline lakes, including caspian, aral, and salton seas. They are not true seas because they are land locked.
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oceanography
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is a multi discipline science studying the world ocean.
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Ocean Water
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ocean water on average 3.5% dissolved solids
contains sediments that obscure visibility.
Phytoplankton and other mine organisms affect ocean color.
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Salinity
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the measure of all the dissolved solids in the water.
includes
oxygen and carbon dioxide
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Pressure
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pressure increases rapidly with depth
surface pressure = 14.7 lbs/square inch ( 1 atmospheric).
1 atm for every 10 m
scuba can only go 100
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salinity
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increased by evaporation and decreased by inflow from rivers
Hot, arid regions have higher surface salinity (subtropical)
humid regions have low
polar regions have low
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basic topic of physical oceanography
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ocean circulation
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the sun
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what drives ocean current?
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warm water rising to the surface and cold water sinking
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What drives ocean currents?
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Temperature
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ocean surface temperature globally reflect air temperature patterns in a general way.
ocean circulation moves warm water from equator toward higher latitudes.
sun heats surface but cold dense water sinks
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Thermocline
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the zone of rapidly changing ocean temperature
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four components that determine heat flux
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incoming solar radiation
outgoing back radiation
heat loss from evaporation
mechanical heat transfer between the ocean and the atmosphere.
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stratification
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cold water moves down, isolating the upper mixed ocean layer from cold deep waters
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wind stress
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What drives ocean currents?
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horizontal circulation
the movement of water as influenced by the Coriolis effect and gravity.
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What drives ocean currents?
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The Ekman Spiral
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Top layer driver forward by wind
each layer below is moved by friction
each succeeding layer moves at a slower speed and at an angle to the layer above
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Vertical Circulation - Upwelling
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in the eastern parts of the oceans permanent equatorward winds generate offshore Ekman drift coastal upwelling of rich in nutrients waters resulting in high primary production.
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upwelling examples
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upwelling occurs along coasts where winds blow parallel to the coast such that net drift is away from the coast
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Anticyclonic
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the general circulation in all oceans is THIS clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
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Flood Tides
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as water rises, incoming water is referred to as this
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Slack Tide
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As water peaks, it is at high water and the lack of tidal current is called THIS
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Ebb tide
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as the water falls, the receding water is THIS
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Ocean Tides
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Rise and fall due to the gravitational force of the sun and moon
can occur on diurnal (daily)
Semidiurnal (two high and low daily)
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Tidal Bore
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wave that moves up a river or narrow bay under unique circumstances
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Properties of ocean waves
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crest
trough
height
length
period
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Progressive Waves
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move across the sea surface
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Standing waves
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oscillate about a fixed point
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Wave Motions
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Two basic motions associated with an ocean wave
the forward movement of the wave form
the orbital motion of water particles beneath the wave
IT IS ENERGY NOT WATER MOLECULES THAT MOVE ACROSS THE SURFACE
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deep water waves
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waves do not interact with the seafloor
orbits of the water molecules are circular
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Life history of ocean waves
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waves originate in the fetch area. This area is characterized by a "confused" sea state with extensive wave interference. This interference may be
constructive
destructive
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Wave Trains
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as waves move away from the turbulent storm that caused them, they sort themselves out by wavelength (and speed). Groups of similar waves are known as wave trains or "sets"
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Progressive Wave Types
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Wind-generated waves are progressive waves because they travel across the sea surface
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Sea Waves
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irregular waves in the area of generation
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Swell
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more regular waves beyond area of generation
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Surf
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waves that have reached the coast, grow in height, and break
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Shallow waves affected by bottom
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in shallow water, the sea bottom transforms the wave's properties. This leads to wave refraction and waves collapse forming surf
bottom friction alters both
wave form
wavelength shortens, height increases
celerity (speed of wave form)
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Shallow water waves
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waves do interact with the seafloor
orbits of the water molecules become elliptical
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At the shoreline
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water becomes shallow, wave height increases because wave length decreases
waves become steeper, then collapse
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surf at shore
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sequence of breaking waves
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swash at shore
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water sliding up beach
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backwash at shore
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water flowing back down beach to sea
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wave refraction
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close to coast, water gets more shallow
waves are slowed down
if waves arrive at an angle, one part is slower than the rest
causes waves to bend = wave refraction
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beach profiles
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gentle summer swells build beach by pushing off-shore sand bars back onto the shoreline, forming a BERM
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overfishing and extinction
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75% of most commercial fish are overfished
big fish are becoming scarce
smaller fish are next
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Continental Margin
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the transition between continents and deep oceans follows a typical form
shallow oceanic floor near the continents is geologically part of the continents, but the oceanic floor is geologically distinct.
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Continental Slope
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between the continental shelf and the ocean floor is a slope called THIS
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The ocean floor
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we know more about moon or mars then we do this
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islands
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form when a part of the ocean floor breaches the surface
many islands are formed by volcanism and therefore not related to the continent
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Atoll
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when a volcano rises to the surface, forms a coral reef, then sinks back, the reef continues to grow, forming a ring shaped island called this
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coral reefs
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shallow, wave resistant structures formed by the calcium carbonate of tiny animals
most diverse communities
need sunlight
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fringing reef
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coral attached to the coast
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barrier reef
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offshore and associated with sinking islands or broad continental shelves
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Structure of earth
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layered structure
radius of 6400 km
composed of iron and nickel
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Inner Core of Earth
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solid
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outer core of the earth
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liquid
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core temperature
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3000-5000 C
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Mantle
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the largely plastic layer between the core and the crust
ultramafic rock
2900 km thick
temp near 2800
brittle outer layer
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Mohorovicic Discontinuity
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contact between crust and upper mantle
aka moho
marks change in density
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Mafic
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close to the surface below the ocean floor
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Felsic
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Deeper Under Land
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Lithosphere
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the solid upper part of the mantle plus the crust is often referred to as...
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Asthenosphere
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layer of soft, plastic rock in the mantle
beneath the lithosphere
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lithosphere and asthenosphere
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stiff, brittle lithosphere moves over the asthenosphere
the lithosphere is fragmented into lithosphere plates
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Continents
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young, dynamic alpine belts
old, stable continental shields
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Oceans
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long, narrow midoceanic ridges
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Alpine Chains
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include mountain arcs and island arcs
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Continental Shields
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low lying older areas of igneous and metamorphic rocks
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ancient mountain roots
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remains of mountain belts in shields
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Alfred Wegener
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proposed that landmasses were once united as (PANGAEA), then split into LAURASIA and GONDWANALAND
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Lithospheric Plates
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there are 7 major plates and many smaller ones
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convergent boundary
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collision, plates come together
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transform plate boundaries
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plates slide adjacent to eachother
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Plate Divergence
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new crust is created and forced outwards from a RIFT
upwelling magma creates new crust and younger rocks
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Seafloor spreading
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most occur at mid oceanic ridges
mid atlantic ridge at iceland 1.8 cm/yr
south atlantic 4cm a year
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Plate Convergence
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continental crust is lighter than oceanic crust (oceanic crust is subducted)
subducting plate has earthquakes that get deeper as the plate goes under the overlying plate.
causes large earthquakes, volcanism, mountain ranges
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oceanic-oceanic plate convergence
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produces deep ocean trenches and many volcanoes
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continental - continental plate convergence
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produces thick land mass, earthquakes, but very little volcanism
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Lateral (transform) plate contact
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two plates are sliding past one another at different rates
is accompanied by frequent earthquakes
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Earthquakes
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movement along a plate, fault of a point of weakness
the greater the movement, the greater the magnitude of the earthquake
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Focus
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origin of the quake
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epicentre
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the point on the surface directly above the focus.
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Global Earthquake Distribution
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80% occur on the Circum Pacific belt
also trans eurasian belt
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U.S earthquake distribution
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most earthquakes in the US occur along the San Andreas fault zone in southern and central CA, or along alaska
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Richter Scale
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open ended from 0 to 8
logarithmic
a 4 causes 10 times ground motion
and 100 times a 2
2 equals 30 lbs TNT
5 small atom bomb
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earthquakes and magnitude
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moment magnitude
amount of fault slip, area required and materials faulted
reassessed old earthquakes
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Mercalli intensity scale
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scale was developed as a measure of earthquake activity based on what people feel at the surface
descriptive not quantitive
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orographic effect
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global air conditions + landforms / physical features = precipitation and local weather
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climate zones
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landforms / physical features + precipitation / local weather
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Vegetation Regions
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landforms / physical features + climate zones = Vegetation
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Natural Vegetation
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the plant cover that would establish itself in an area without human interference
many areas of the earth have been modified by humans
climate changes with latitude and longitude are reflected in changes in vegetation. These changes are gradual not abrupt.
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biomes
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consist of:
global air
landforms / physical features
precipitation / local weather
climate zones
vegetation
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Earths major biomes
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type of biome controlled by temperature and precipitation
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Forest Biome
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low latitude rainforest
monsoon forest
subtropical/ temperate evergreen forest
midlatitude deciduous forest
boreal forest
schlerophyll forest
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low latitude rainforest
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found in equatorial and tropical zone
continuously warm temperatures with consistent abundant rainfall
a forest of tall, closely set trees with multilayered canopy
largest diversity of species of any lifezone
graph high medium
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mid latitude deciduous forest
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sheds its leaves in winter in response to the cold temperatures
hot summers, cold winters
moderate precipitation
oaks, hickory, maple
graph medium throughout
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boreal forest
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few species of tall cone shaped mostly evergreens
trees create a continuous deep shade at ground level which inhibits growth of shrubs
high elevation mountainous
low precipitation
graph low medium low
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Savanna biome
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a product of the tropical wet-dry climate
changes from woodland to thorn tree grassland with increasing dryness
adaptation to dryness includes deciduous habit and small leaves or thorns
trees are widely spaces and area is prone to fires.
graph: high low high
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Grassland Biome
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midlatitude and subtropical zones with well developed winter and summer
includes both tall grass prairie and steppe
steppe vegetation grows in the semi arid subtype of the dry continental climate.
Graph low high low
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Desert Biome
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includes both desert and semi desert
semi desert ranges from mid latitude to tropical
wide variation of temp
very dry
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tundra biome
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found at high elevations and latitudes
permafrost restricts drainage and root development
very short growing season
little precipitation
low diversity
graph all low like desert
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GEOG 2300: CHAPTER 12