Exam 2 Flashcards

Question

atmosphere pressure and water vapor

Answer 1

◦ Air seems to have little density, but if there was not internal fluid pressures in air…we would be crushed ◦ Atmospheric pressure is greatest at sea level and drops rapidly with increasing altitude • At 8.8km, height of Mount Everest, the air is so thin that humans can't get enough oxygen in each breath to survive water vapor -- ◦ Water removed from oceans by evaporation and carried as water vapor in turbulent troposphere ◦ Has a warming influence on atmosphere - called the "Greenhouse effect" ◦ Condenses to form clouds - controls amt. of solar energy that is reflected away from Earth ◦ Cold air can hold much LESS water vapor than warm air • % of water vapor at poles is 10 times less than at the equator - also water vapor high in atmosphere is much less than at the surface ◦ Precipitation occurs when air is oversaturated with water vapor - occurs when vapor is no longer stable form of water but must be joined by liquid as well - condenses to form droplets of liquid water/ice that falls to the earth • Most precipitation occurs along the equator - the least falls in deserts N and S of the equator and also in polar zones

Answer 2

Driven by uneven distribution of solar energy - solar heating is greatest in equator and causes water in oceans to evaporate and moist air to rise ---Bordered in middle latitudes by high-pressure zones that are cloud-free and have dry air Solar radiation and heat balance - --Large part of sun's radiation is reflected back to space immediately - 30% reflected by clouds, oceans, ice and snow covered areas (bright areas) - --As the surface warms - it radiates heat back to space and warms lower atmosphere in the process - --The amt. of solar radiation absorbed by earth decreases with the distance from equator (bc gets colder closer to poles) 1. Earth is a sphere, angle at which sun's rays hit surface varies from nearly vertical as the equator to nearly horizontal to the poles 2. Also less energy received at poles bc same amt. of incoming radiation is spread over a large area bc of the angle - the same energy is concentrated in a much smaller area at the equator 3. Sunlight also travels through much greater thickness of atmosphere near poles than at the equator - which diminishes the amt. of heat that reaches surface 4. Also length of the day - tilted 23.5 degrees - length of day varies with the seasons - during winter, days are shorter bc the spin axis is tilted away from the sun

Answer 3

◦ Systems try to reach equilibrium - global circulation of atmosphere is an attempt to reach equilibrium by equalizing temp. diff. btwn poles and equator - this movement in the wind causes circulation of oceans and atmosphere - drives climate ◦ Constant movement revealed in clouds and distribution of water vapor * If movement due to solar heating, hot air would rise at equator and flow toward poles - as cooled, would sink at poles and return to equator - surface winds flor straight from poles to equator * CORIOLIS EFFECT - Newton's 1st law of motion: body in motion keeps speed and direction unless acted on by an outside force - force divides atmosphere circulation into several latitudinal zones - flows in 3 separate loops: tropical, temperate, and polar cells are spiraling convection cells that stretch around the planet uneven wind patterns caused by uneven ditribution of solar radiation in combo with earth's rotation - -neat equator - air heated which reduces density and air rises - at high alititues, air cools and desvends towards equator - trade winds - -in N, deflected by earth's rotation and flows s (S moves N) - -when warm moist air flows from south cools it drops as rain or snow

Answer 4

◦ Two rules of the global transport patterns of water in hydrologic system 1. Evaporation rate increases with temperatures 2. Warm air holds more water vapor than cold air 1. So the water near earth's equator has higher evaporation - also higher precipitations rates ◦ Circulation model • In equator, hot, moist air rises bc of low density in warm air - as it rises and cools the moisture condenses - the condensation produces tropical rains which fuel growth in South Am. Africa and Indonesia ▪ The Coriolis effect - Creates trade winds that converge toward the equator and creates intertropical convergence zone

Answer 5

- -Water vapor by evaporation over oceans is major source of water that falls as rain on continents - --Major sources of water that falls on continents are areas of ocean where evaporation exceeds precipitation (closer to equator - symmetrical on both sides) - most important zone of water for continents and rivers - --Areas of intense evaporation are the major source of water for the Amazon river Monsoons - Occur when a wet season is followed by a dry season as prevailing wind directions reverse direction • Regional not global pattern - controlled by plate tectonics • During winter, Asian continents become very cold and high pressure zone develops - the cold, dry air push zone over indian ocean - forms dry season - intertropical convergence zone south of equator • During summer - becomes a hot, low pressure zone - intertropical convergence zone to the North of Equator - warm wet air moves over Himalayas - air cools and heavy rains fall • Monsoonal rains feed almost half of world's population

Answer 6

Oceans cover 70% of earth's surface and contain 97% of earth's water - major source of water that evaporates and precipitates on continents - oceans can store heat which moderates seasonal climate changes - oceans help moderate temp. diff. from equator to pole sea water - NaCl - salnity is measure of all dissolved salts in sea water - varies with amt. of fresh water inputs from rivers or melting glaciers -- ◦ Salinity high in sub-tropical regions bc intense evaporation leaves water rich in salts that cannot evaporate • At high latitudes, temp. is lower and evaporation rate is lower - fresh rainwater makes surface waters low in salinity ◦ Salinity also greater jus below the surface of sea ice, bc ice rejects the dissolved substances, thus enriching them in the liquid beneath frozen ice ◦ Highly saline waters are more DENSE ◦ Differences in salinity and temp. drive the circulation and flow of seawater

Answer 7

• Water has one of the highest heat capacities of any substance - ocean waters can store, transport and release heat - affects earth's weather and climates • Ocean temp. decreases with depth (Ave. temp. is 3.5C) ◦ Near surface, seawater almost same temp. as atmosphere - freezing deeper ◦ Diff. btwn temp. btwn surface and bottom water is small at the poles 1. Surface water ◦ Ocean layered bc of temp. differences (like atmosphere) ◦ Warm and less dense - well mixed bc stirred by winds, waves and surface currents - exchanges water vapor and Co2 - bc very mixed, temp. and composition vary only slightly (comparable with troposphere) 2. Deep water ◦ Dramatic temp. drop - almost uniform temp. that changes very little n and S of equator ◦ Very thick and contains most of ocean water - moves slowly - bc so dense, makes it difficult to move upwards and mix with surface water - so stratification is stable - almost completely isolated from atmosphere • Sea ice - increases the amt. of solar energy that is reflected into space - reflects more solar energy than darker seawater - covers up to 15% of the earth's surface - permanently present on 7% of ocean ◦ Thin -sea water freezes at colder temp. (-2 degrees C) bc of salt (fresh is 0 C) (thinner in Antarctica than Arctic)

Answer 8

◦ Along shorelines, coastal upwelling of deep-ocean water is imp. - bc of Coriolis effect, winds blowing toward equator and along coast cause seawater to move to right of wind direction in N and to left of wind direction in S - movement of surface water away from shore causes cold deep water to flow upward and take its place - the deep water is rich in nutrients and turns into food for sea animals (Cali) ◦ El Niño - (The Child) - occurs around Christmas - sometimes when wind weakening allows warm currents to approach shore of S Am. Where surface waters are usually cold - causes plankton pop. To diminish and fish pop. To almost disappear (bc surface warm water lacks nutrients) - bird pop. Diminishes and fisherman are out of work - causes flooding in N and S Am. And drought in India, Indonesia and Australia

Answer 9

Climate change evident in sedimentary rocks ---Huge temp. changes have not occurred on earth - earth has been cool enough for liquid water to exist for 4 billion years - nearly constant temp. 1. Regional change due to continents moving into diff. climate zones ◦ Slow movements of lithosphere (plate tectonics) - over long span of time - move in certain direction over thousands of years, but also obstructed by plate collisions - possible, but earth's climate has remained relatively unchanged 2. Global climate change - human disturbance ◦ Most imp. Global climate parameter is temp. - change could be caused by energy output of sun composition of earth's atmosphere, reflecting of earth and its atmosphere, ocean circulation patterns, blocking of sunlight, or changes in earth's spin/orbit ◦ Greenhouse effect - Co2 in atmosphere absorbs heat radiated from surface and traps it in troposphere - gases that absorb energy an inc. atmosphere's temp. called greenhouse gases - CO2 concentrations have been inc. since 1800 - inc. from 275 CO2 to 400 in past 250 years - inc. c02 from fossil fuels (coal, oil gasoline all fossil fuels - burn to release CO2) - inc. dramatically since 1800 industrial revolution - causes global temp. to rise ◦ Ocean acidification - also inc. CO2 in atmosphere bc of increasing acidity of oceans - when co2 is released it accumulates in oceans where it reacts with water to make a weak acid - ph of ocean is 8.1 - causes it to cont. to drop - lower ph makes it diff. for corals, plankton and other sea creatures to precipitate skeletal minerals

Answer 10

is the physical and/or chemical alteration of rocks and minerals where the lithosphere, hydrosphere, atmosphere, and biosphere meet - -breakdown of rock's at earth's surface by physical processes and chem. reactions with air and water - -weathering is process of NATURAL DECAY (buldings deteriorate, wood dries and splits, cement crumbles) - all happens bc rock materials exposed to atmosphere

Answer 11

1. physical breakage of rocks into smaller pieces by phys. processes - no chnge in chemical composition 1. Ice wedging - --Water expands when it freezes - volume increases by 9% (in pic. It looks like the water seeps inside rocks and when it freezes it expands and the rock grows in volume and tends to crack with the new pressure - --This occurs where daily freeze thaw takes place - at least seasonally - --Talus cones - -water from rain or snow penetrates cracks or openings in rocks - as it freezes..it expands and puts pressure on the rock walls - over time the rock is hammered out - -occurs when lots of moisture exists in env, when there are lots of cracks in rocks, when freq. temp. rise and fall beyond freezing pt. - -in arid regions, salt crystals grow in pores and cracks to pry apart rocks - grow by evaporation as rocks exposed on salty shores - SLC 2. Sheeting - --Release of confining pressure - --(1) Deeply buried pluton - (2) mass exposed by erosion of overlying soil - (3) pluton expands outward and is exfoliated - --rocks deep within earth's crust are under pressure from above rocks - as cover removed by erosion, pressure is released and buried rock tends to expand - causes internal stress that leads to fractuers in rocks - causes them to burst 3. unloading talus - product of phys. weathering - best seen in mountains - material accumulates in pile at base of cliffs - called talus cones - built up of isolated blocks loosened by phys. weathering - piles of rock debris that accumulates. at base of cliff as result of rock fall - usually by ice wedgine Tree roots ---Root tips pressures may exceed 10,000 kg per square meter --also caused by animals and plants - they mix soil and loose rock particles to cause further chem. breakdown - pressure from growing tree roots NO CHANGE in chemical composition - just breaking down into small pieces

Answer 12

Proceeds by the removal or addition of chemical components to the minerals, changing the composition and internal structure of rocks --many scientists believe chem. most imp. 1. Dissolution - --Headstone example over the years - dissolving - -process where mineral passes intosolution, like salt dissolving in water - some in water and ions are leached (flushed away) - salt (halite) is best ex - extremely soluble - Gypsum also - -almost all minerals are soluble in water (ionic bonds are easier than covalent) 2. Acid Hydrolysis - -most common dissolution reactions involve acidic water - -H2CO2 common in natural env. and forms when water combines with CO2 - happens in atmosphere or root zones of plants when CO2 is in soil - -hydrolis is chem. reaction where water and another substance both decompose into ions - -in pure water, calcite not very soluble, but water in carbonic acid can dissolve more - -can cause formation of new minerals - new minerals are "hydrated" - -best Ex. is Feldspar partly altered to a mixture of clay and quartz - -effect only really seen in microscope - weathering caused feldspar to turn to clay 3. Oxidation ---Combination of oxygen with one mineral to form a completely diff. mineral where one element has a higher oxidation state (higher ionic charge) --chem. combo of oxygen in atmosphere or dissolved in water - one mineral to form diff. mineral at higher oxidation state --iron is most imp. - better in oxidized state ▪ Ex. Fe2+ becomes Fe 3+ LOOK AT TABLE 10.1 - to see which minerals are most susceptible to chemical weathering - Gypsum and halite are quick and easy - Quartz resists dissolution, Pyrite is lowest on table

Answer 13

Principle: mechanical weathering enhances chemical weathering by producing more surface area - chemical weathering proceeds at the surface of a mineral --permits deeper penetration of reactive fluids that cause chem decomposition - chem decay facilitates physical disintegration

Answer 14

Decomposition is most rapid at corners ---Further weathering reduces size Differential weathering - -Caused by variations in weathering rate - --Occurs over a broad range of scales - -Appalachian mountains, Arches, spindles - -diff. rock masses or sections of same rock weather at diff. rates - can be seen everywhere - Bryce anyone - white layers erode more rapidly than thicker beds of sand which are more resistant

Answer 15

The nature and amount of soil found in a particular place is related to factors affecting weathering rates and the ability of the soil to stay in place ``` • topography • Parent material •Soil is earth material that is capable of sustaining rooted plant growth • Vegetation • Time • Climate Soil structure ---Soils are more weathered at the top - dissolved matter from the top of a soil column travels downward and is deposited in lower portions ``` rates of weathering - linked to climate zones - human structures useful gages for measuring rates - thickness of soil profile controlled by weathering rates

Answer 16

facilitate weathering bc permit water and gases in atmosphere to attack a rock body at considerable depth - also inc. surface area on which chem. reactions can occur major products of weathering - spheroidal rock forms, blanket or regolith and dissolved ions --soil is upper part of regolith (mixture of clay minerls, weathered rock partciles and organic matter) climate and rock type influence type and rate of weathering - also helps control amt. of CO2 in atmosphere and thus climate

Answer 17

minerals in rocks are in equilbrium - butwhen exposed to diff. env. the minerals have to adjust to diff. forms that are stable under new conditions --metamorphic and igneous intrusions most susceptible to weathering

Answer 18

influenced by variables: mineral composition, texture, climate in which weathering occurs --ex. limestone could weather into soil-covered valley in humid climate and form cliff in arid climate minreal composition imp. - quartz is stable and remains unaltered where olivine and feldspars are unstable and decompose immediately texutre imp. bc of porosite and permeability - ease at which rock can enter and attack minerals --precipitation amts. also influence granite - most homogenous rock - forms at high temp. and under great pressure - -delspars weather rapidly by chem. reaction with water - altered to various clay minerals - -calcium is resistant in calcium feldspars - -basalt - is vesicular and porous - easily broken down pjhyiscally - permeable and easiy composed - -sandstone - composed of quartz - resistant to chem. weathering - -shale is fine-grained and soft - composed of clay and has ability to absorbe and expel large amts. of water

Answer 19

LOOK AT PG. 279 major products are 1. rock bodies modified into spherical shapes -almost all rocks broeken into fractures that influence the weahtering of rucks by cutting blocks of rock to smaller ones (inc. surface area for chem. reactions to take place) - breakdown of rock to joint planes called joint-block separation --joints also act as system of channels through which water can readily attack a rock from several sides ---tendency for\ spherical (rounded) surfaces to form as decayaing rock breaks - produced bc weatheing attacks all exposed sides of ricks at once - decomposed material falls off and leaves round shape --exfoliation - type of spheroidal weathering where rock breaks apart by separation along series of concentric shells or layers - layers are parallel to each other and surface - could bring sheeting in granite

Answer 20

2. blanket of loose, decayed rock debris called regolith (soil is most imp.) - -forms a discontinuous cover over solid, bedrock below - loose, soft material formed in place by decomposition of bed rock beneath it - within regolith, the indiv. grains or small groups of mineral - -transition from bedrock to regolith - -gravel, sand, silt and mud deposited by streams wind are transported regolith - cover the surface - -on steep canyon walls, little soil is retained and bedrock is exposed soil --uppermost layer of regolith - compose of small particles of rock, new mienrals formed by weathering and amts. of decomposed materials soil profile - transition from upper surface of soil down to fresh bedrock - shows all the layers (horizons) of soil by compositon, color and texture - -A horizon - topsoil layer - usually dividied into 3 layers too (A0 thin surface of leaf mold), (A1 humus-rich dark layer), (A2 light, bleached layer) - -B horizion is subsoil - contains clays washed down from topsoil - Zone of accumulation and reddish in color - -C HORIZON - zone of partly disintegrated and decomposed bedrock - meets the bedrock topography - affects soil development bc influences the amt. and rate of erosion and nature of drainage - -influene is seen from contrast btwn slope soils and veley soil - thick soils from on flat or gently sloping surfaces but steep slopes permit only thin soils to develop - -time also imp. in soil development - seen in areas of volcanism - thick soils have developed on old lava flows - thin soils on younger flows

Answer 21

3. ions in solution - -ions dissolved in water - -major source of ions in solution is carbonate rock - 45% of dissolved material in rivers is derived from carbonates

Answer 22

cliamte is the SINGLE MOST IMP. FACTOR influencing weathering - determines type and rate of weathering but also characteristics of regolith and rock surfaces - -intense chem. weathering occurs in hot, humid regions and develops thick regolith - it is minimal in deserts/polar regions - -bc rainfall, temp. and seasonal changes impact weathering style and rate - -most chem. reactions req. presence of water - precipitation of an area is huge factor!! physical weathering - most imp. infleunce is temp. changes that produce cycles of freezing and thawing chemical weathering also controlled by temp. and water acidity (pH level) - from 1 acid to 13 alkaline (iron is MUCH more soluble at pH 6 than pH 8.5) - so forests exp. more chem. weathering than other areas --physical w. dominates arctic areas (thin soils) and che. in tropical (thick oxidized soils)

Answer 23

OXISOLS - dominate tropical zones in Afica and S Am. - high temp. in tropical areas SPEED chem. reactions ARIDOSOLS - low-latitude deserts where chem. w. is minimal bc of lack of precipitation - soil is thin temperate regions - temp. and humidity range so both chem. and phys. w present - soil and regolith develop to depths of diff. meters --MOLLISOS - organic rich A-horizon thick soils dominate temperate zones GELISOLS - soil is thin and unproductive - in polar regions - temp. too low for chem. weathering - env. for physical w. - -climate also affected by weathering - chemical reactions involving carbon create chemical cycles - can remove CO2 from atmosphere - imp. bc co2 is greenhouse gas and when removed it reduces atmosphere's ability to absorb heat and the planet cools - -other side - CO2 can be released into atmosphere by weathering - produced by black shales - carbon reacts with oxygen or oxidized groundwater to create co2 - so co2 and temp. rise!!

Answer 24

rates measured by tombstones, buildings, monuments, volcanic ash - Egyptian pyramids - -Great Pyramid of Cheops - originally had polished limestone - blocks protected tje rock from waethering until the outer layers were removed 1000 years ago - now waethering has attacked all 4 main rock types used in construction - least weathered is granite - and hard limestone - -in Mexico, pyramids have been deeply weathered rate processes decompose and break down a solid rock body depends on: 1. susceptibility of consituent minerals to weathering 2. climate 3. amt. of surface exposed to atmosphere

Answer 25

May 31, 1970 - Huascaran Peru - the day that Yungay died - -avalanch swept 9 miles at 100+ mph - triggered by an earthquake (mag 8) - -70,000 fatalities - 19,800 from the avalanch and 50000 from earthquake - -15 M cubic meters of rock and ice types of mass movement (includes all types of slope failures) - picture --classified by: type of MOTION, type of MATERIAL, RATE of movement

Answer 26

1. CREEP - -extremely SLOW movement of soil and regolith (1-10 mm/yr.) - soil and rock - -combination of factors cause creep - heaving of soil (Expansion and contracting is the primary cause) - -also wet-dry cycles and freeze-thaw cycles very slow movement of soil and rock produced by expansion and contraction of surface materials --signs are seen in curved tree trunks or tilted posts, deformed roads and fence lines SOLIFLUCTION - -creep that occurs in permafrost (layers of permanently frozen ground) - as ground thaws from surface downward - so meltwater causes saturated upper soil zone that flows slowly downward - -melting of soil water occurs from the surface down - permafrost prevents downward percolation - surface soils become saturated and begin to flow other slow mass movement is rock glaciers - which resemble glaciers in form made of debris and ice - melting of ice moves the mass

Answer 27

2. Slump block (pics) - -spoon shaped slippage plane - -block moves downward and outward - -usually have multiple slippage planes - -bedding plane displacement provides evidence for movement material moves as a unit along definite slippage planes (happens in slumps and landslides) --where rock falls are the free-fall of a single fragment ranging from small grains to huge blocks that may break up and become fluid as they flow

Answer 28

3. debris flows - -mixture of water, mud and rock - -liquidifed soil flows downhill (up to 50 km/hr) - -water lubricates mass of soil and rock - -boulders and building etc. may be carried - -pic. of mudflow in Idaho - usually occur during intense rainfall or sudden thaw - -most common in wet climates debris flows are mixture of rock fragments and water that flow rapily downslope as viscious fluid --LAHAR is special type of debris flow composed of volcanic materials mudflows are with debris flow - small silt and clay-sized particles - 30% water

Answer 29

4. slides - -landslides diff. than creep and debris flow in their mechanics of movement (landslides are very common) - -landslide block above i the slump block landslides occur along well-defines slippage surfaces - large blocks slump and rotate downslope and many grade into debris flows at their lower margins - -along well defined slippage plane - -landslide block moves as a single or group of units - -rock type, orientation and water content influence evens - -thistle slide - spanish fork Utah, Washington 43 dead/ missing in 2014 (bc 200% of nomral rain fall) - Brigham Canyon slide in 2013 rock slides (rock and debris) (diff. than rock falls) - rock slides move rapidly - large block of rock along bedding plane, joint or point of weakness - -stress exceeds cohesive strength of any plane of rock and initiates rock slides - usually on mountains VAIONT DAM DISASTER Oct. 1963 - WORST dam disaster in history - killed 2600 people - rock landslide

Answer 30

1. GRAVITY - -weight of rock on hill is 1kg, force directed downhill is .5kg and the cohesive force is ,87 - pushing it towards ground 2. Fractures unconsolidated rock and dirt - peices and pebbles of rock 3. stability of slope 4. role of water (look at angles of repose pic.) acting to inc or dec. cohesive strength - -dry regolith or soil has little or no cohesion - -damp regolith or soil is sticky - -saturated regolith or soil flows easily - -water in pore spaces can bind partciles - but water btwn all particles keeps them apart and allows them to flow 5. planes of weakness (become weak by fire removing vegetation or water) - California ex. fire removed vegetation and allowed landslide to occur 6. triggering mechanisms - -earthquakes and vibrations - -slope angle and undercutting - -climate (Water, plants and weathering) - -volcanoes - -human activities - -underwater landslides DO occur - happened in Santa Barbara, or New Guinea from 50 foot tidal wave saturation of slope material with water, earthquakes, over steepening of slopes, freezing and thawing and strenght of materials on slope

Answer 31

is vertical motion causde by collapse into voids or as a result of compaction of loose materials - -downward movement of earth material lying at or near the surface - diff. than other types bc it is VERTICAL - primary force is gravity - -formation of caves is major source of subsidence rock falls - -free fall of a single fragment ranging from a small grian up to huge blocks - -over time, moderate weathering products shower down cliff and accumulate at base as talus rock avalanche - is DRY (not fluid) - huge in Alberta, Canada subaeueous mass movements - affect large areas of seafloor - very common!! - steep slopes - usually triggered by earthquakes or storms

Answer 32

gravity is cont. force but can only move material when it exceeds the COHESIVE strength of the surface material - -as products of weathering accummulate on a hill, the dry loose rock fragments tend to accumulate at a nearly uniform slope angle incluned at what geologists call the ANGLE OF REPOSE - -this angle is the steepest slope at which loose material (talus) will remaub at rest without rolling further downslope (slope at equilibrium is the angle of repose) - look at picture

Answer 33

longest = Nile Deepest = Congo Most water = Amazon Hydrologic cycle is the cycling of water btwn the oceans, land, atmosphere and mante on earth - -97% of water in oceans - -2.8% split among glaciers, groundwater, and SMALLEST % in lakes, rivers, streams every river has a WATERSHED or area where rain is collected to form the river

Answer 34

laminar (just straight) - -very low or very high water velocity - -less common condition in streams turbulent - -usual flow condition of streams - -provides upward force to transport sediment factors affecting stream flow 1. discharge - the volume of water flowing past a given point in the river - varies with time and weather 2. stream gradient - -gradient is the slope of the stream channel - steepest in headwaters and decreases downslope 3. velocity - -higihest velocity is the centr of the channel - drag causes water to slow along the bottom, banks and top - -velocity is proportional to the gradient of the stream channel - rapid with sleep slopes and waterfalls - -where a stream appraoches ocean, the velocity is reduced to 0 - -velocity not uniform throughout stream channel - -velocity controls a stream's ability to erode, transport and deposit sediment 4. sediment load - -material carried along by the stream in 3 ways 1. suspended load (fine particles) - -most obvious and common - silt and clay 2. bed load (coarse particles - big rocks) - moved by traction - move by sliding or rolling and salting 3. dissolved load (ions in solution) - carried in solution - -running water is MAJOR source of erosion bc it can abrade and erode channel but also bc it has HUGE power to tranport loose sediment produced by weathering - -medium by which regolotih is picked up and transportde to ocean - -stream is very turbulent - -competance (Streams ability to carry heavy particles) increases with velocity 5. base level - -lowest level to which a stream can erode its channel - it is the elevation of the stream's mouth, wheter stream enters an ocena, lake or stream

Answer 35

base level - the lowest level to which a stream can erode its channel --lake, ocean, another stream/river river equilbrium - change any factor and moves towards equilibrium --GRADED STREAM is in equilibrium as rivers travel down gradient they erode sediment from the surrounding rock - erosion by means of: 1. abrasion (controlled by velocity and loa) 2. sediment removal (velocity) leads to 1. downcutting 2. headward erosion - -Niagra falls rivers not in equilibrium bc of urbanizatioimpacts - construction of cities -change river dynamics

Answer 36

braided stream - result if a river system is supplied with more sediment than it can transport --deposit excess material on channel floor as sand - deposites may force stream to split into 2 or more channels which forms interlacing network of braided chanels and islands (common in arid regions) deltas - most of the rivers sediment is deposited where the river emptires into a lake or ocean - deposition can bulid a delta at the river's mouth - -distributaries include splays -crevasse amd avulsion (Avulsion is when distributaries cannot go to ocean and something forces htem to change direction - usually during flood) - -splay is when reduced velocity causes deposition of sediment in a fan-shape - -shape of the delta depends on the balance btwn fluvial and marine processes - -Mississippi delta is swamp and channel deposits, Nile is lagoonal swamps, barrier beach and deltaic plain (bc wave actions) alluvial fans - form in arid regions where streams enter dry basins - sediment is deposited as gradient becomes smaller - -it is a stream deposit that accumulates in a dry basin at the base of a mountain front - -diff. than deltas - delta has sediment that is deposited in a body of water, upper surface limited by size of ocean or lake - fan is deposited in dry basin and uppersurface is not limited by water level

Answer 37

FLOODS ARE THE MOST FREQ. AND LETHAL OF AL NATURAL DISASTERS (flood SLC in 1983) --Occur no matter what - flood control work WITH nature not against it floodplain --On gentle slopes of shields and stable platforms, stream valleys are covered with sediment that makes up a flat surface over which stream flows - surface is FLOODPLAINS - during floods can be completely covered in water all rivers flow in sinuous pattern - water striking on side causes erosion and undercutting, which can make bends and curves in the river channel - -small curve can grow into a large MEANDER - inside meander, velocity is lower - -then some of the sediment is deposited on the point of hte meander bend called the POINT BAR - caused by erosion on outside and deposition on the inside - can create a crescent shaped lake called an OXBOW lake - -NATURAL LEVEES - are high embankments on both sides of the river - forms during floods when river is no longer confined to a channel but is on land - coarse material builds up - grows with each flood backswamp - grows as natural levees grow - poorly drained site of marhsed and swamps --forced to enter YAZOO STREAMS - streams that run parallel to the main stream

Answer 38

network of connecting channels through which water is collected and funelled back to the ocean - -constantly adjusting towards equilibrium - -controlled by tectonicand hydrologic system - -picks up weathered rock debris as it carries it to oceans - -also form hills and swamps and valleys - -driven by energy fro the sun and gravity - OPEN system RIVER systems are the most important agent of erosion!

Answer 39

main channel and all the tributaries that flow into it - -divided into 3 subsystems - -river system also called drainage basin (bounded by a DIVIDE (ridge) beyond which all water is drained into another system (wraps the entire river boundaries) 1. collecting system - -network of tributatires in the headwater region that collect and funnel water and sediment to main stream - TREElike (Dendritic) with many branches that go upwards towards the divide 2. transporting system - -main trunk stream - functions as a channel through which water and sedmient flow from the collecting area to the ocean - -works at erosion, deposition and transportation 3. dispersing system - -netowrk of distributaries at the mouth of the river where sediment and water are dispersed into ocean every part of the river is connected - no separate streams - eachstream has tributaries - -the # of stream segments (tributaries) decreases downstream as gets closer to dispersing area - -length is greater downstream - streams are wider and deeper downstream

Answer 40

1. removal of regolith - -removing and transporting loose debris by weathering - net result is a blanket of regolith being removed and transported 2. downcutting the stream channel by abrasion - -downcutting is process of erosion in all stream channels - done by ABRASION if the channe floor by sand and gravel as they are swept downstream by flowing water - -evident in vertical gores of canyons in SW - the movement of sand can cut the stream channel and help form deep canyons - -major tool of erosion is sand and grvael - cut through bedrock as they are moved and crated the gorges and canyons in the Grand Canyon, AZ - -can also drill deep holes called POTHOLES - -waterfalls also move rapidly with strong turbulence - cause rapid erosion of underlying weak rock layers - Niagra falls 3. headward erosion - -sreams have tendency to erode upward - headwrad erosion is constantly extending the drainage upslope so the network of tributaries is enlarged and consumes the flat upland - -as water flows and appraoches the head of tributary valley, velocity and volume are increased and its ability to erode increases - tributary valey erodes headward - -head it the top, the mouth is the ocean or deposit zone with headward erosion - can also interect with another stream called STREAM PIRACY - captured tributary of another stream --point of imminent piracy (can't touch) - pount of piracy where they intersect GRAND CANYON IS A MODEL OF STREAM EROSION

Answer 41

quick sudden short-lived floods that move quickly donnstream - -freq. occur at upper reaches of river especially mountain valleys - -major process in developing alluvial fans - -likely in areas with narrow, deeply incised valleys where river channel is restricted - -narrow cantons of Zions national park in utah - not uncommon for summer storm to cause flash flood evolution of major rivers influneced by climate and plate tectonics --volcanic acivity also

Answer 42

porosity - volume of pore space permeability - ability to allow passage of fluid among pore spaces groundwater flows mainly due to gravity, but sometimes this can cause some of the water to flow upward - -water found at some depth anywhere below surface - -water table shows boundary below which pore spaces are filled with water --zone of saturation is lowest

Answer 43

recharge = infiltration of water into groundwater system --enhanced when water is allowed to penetrate the ground, and retarded when ground cannot be penetrated by water (ex. in forests can easily seep in, but in big cities, 90-100% of the water just flows from concrete into canals, only 9-10% into groundwater recharge 1. steepness of slope 2. heavy vs. light precipitation 3. dense vs. sparse vegetation 4. sediment particle size

Answer 44

aquifers - saturated permeable rocks - may be confined btwn impermeable layers or unconfined and open to surface unconfined aquifers - connected to the surface with open pore space - called water-table aquifer confined aquifers - permeable layer is enclosed by impermeable layers (shale)

Answer 45

chemically weathers and erodes the bedrock through dissolution --forms caves, sinkholes, Karst topography groundwater and limestone - -decomposing organic matter produces CO2 - -co2 reacts with water to form carbonic acid, whcih dissolves limestone, saturating water with calcium and bicarbonate

Answer 46

erosion by groundwater produces Karst topography - -at its max. in tropical areas - bc of abundance of water from heavy rainfall leading to more chemical reactions - -tower karst developed - In China, terrain called peak forest - characterized by steep, cone-shaped hills rather than sinkhills nd solution valleys Karst evolution - -characterized by: (also caves) 1. solution valleys - --where sinkholes grow and enlarge, they merge with others and form an irregular closed depression called solution valleys 2. disapperaing streams - -small streams flow to surface for short distane then disappear in sinkhole and become disapperaing - water moves slowly through system of caverns and caves 3. sinkholes - -large caves that hvae grown until the roof collapses and a craterlike depression is produced - solution enlarges the sinkhole to form solution valley cont. to grow until soluble rock is removed completely most imp. acid in groundwater is carbonic acid (H2CO3) --forms as co2 in atmosphere and soil dissolves in water 20% of world has major limestone sequences at surface and karst topography is limited to those areas --best developed in humid/tropical regions

Answer 47

minerals may precipitate from dissolved ions in groundwater - -co2 in water dissipates into area - -caco3 is precipitated how do we use groundwater as resources?? - -97% of unfrozen fresh water supply - -50% of drinking water - -25% of water used for industrial purposes saltwater intrusion of an aquifer from over-pumping - is very common problem in south Florida - -create a well to get to fresh water that borders salt water - the salt water intercepts and goes into the well - -caused by EXCESSIVE PUMPING - causes cone of saltwater to extend up a well and contaminate fresh water Houston Texas from over pumping - Houston NW - fastest sinking land in coastal area also SUBSIDENCE issue - -sudden collapses (kart like topography) due to natural causes or artifical withdrawal of fluids - -random building collapses into undiscovered caverns below the surface - -MEXICO city subsidence - build on a former lake bed

Answer 48

related to surface water drainage - controlled by porosity and permeability of rocks water table is upper surface of the zone of saturation --naturally discharged into streams, springs, marshes and lakes alteration og groundwater may produce problems like pollution, subsidence, collapse and disruption of ecosystems gravity is the principal driving force for the flow of groundwater - open system --water enters the system as it infiltrates the ground (RECHARGE) - then moves trhough pore spaces of rocks and leaves system in streams, springs or lakes (DISCHARGE)

Answer 49

as water seeps into ground, gravity pulls it downward through 2 zones of soil and rock 1. zone of aeration - pore space is filled with part air and part water 2. below certain level all openings are filed with water - called zone of saturation - the water table is on the upper surface of this zone - -in some humid areas the water table is only a meter deep, but in deserts it can be 100s or 1000s of meters below surface - -within the zone of saturation is unfractured bedrock (no water in between), fractured bedrock (water in cracks) and loose regolith at the top that is filled with water in all spaces - above that is the water table

Answer 50

moves from zones of high pressure to zones of low pressure - -in unconfined aquifer, the diff. in elevation btwn parts of water table called HYDRAULIC HEAD - -water under water table beneath a hill is under greater pressure than water underneath a valley - groundwater moves downward towards points of less pressure

Answer 51

artificial discharge - wells - by drilling holes through zone of aeration to zone of saturation - when well is pumped the water table is drawn down into well in shape of a cone, called CONE OF DEPRESSION - -if water is drawn faster than it can be replenished, zone of depression grows and goes dry - -large cones of depression in big cities and insutrial plants - -result is the smaller, shallow (not as deep) wells nearby go dry and cannot provide water anymore natural discharge - occurs whenever water table intersects surface of ground (discharge is major link btwn groundwater reservoirs and other hydrologic systems) --- springs and geysers geysers and hot springs require: --springs produced in areas where limestone is plentiful and allows water to freely flow to surface, or where there is abnormal growth of vegetation, or when faults displace rocks, or when basalt is exposed on canyon walls --hot rock bodies to heat groundwater --fracture system to transmit water --large supply of groundwater --Geysers such as Old Faithful are results of process (leads to huge eruption)

Answer 52

1. body of hot rocks lie close to surface 2. system of fractures extend downward towards surface 3. relatively large supply of groundwater must be present geysers - -groundwater circulates throgh hot rocks in an area of recent volcanic acivity - temp. of water rises and boils - bubbles grow in size and number and accumulate in geyser tube - -expanding steam forces upward until discharged at surface vent (small discharge) - -preliminary discharge of water reduces pressure on low water - the chambers in geyser fill with steam - -eruption ceases when pressure from steam is spent and geyser tube is empty - -once filled with groundwater, another eruption occurs

Answer 53

Glacial systems - -an oen system of flowing ice - water input as snow, transformed into ice, ice flows under pressure, water leaves by evaporation and melting, systemequilibrium may shift - -shapes the landscape by eroding, transporting an depositing sediment glacier: a body of ice located on land that FLOWS under its own weight 1. zone of accumulation (snow) 2. zone of ablation (melt) 3. snow line (boundary) snow metamorphism 1. snowflake - burial pressure cause melting of needles 2. firn - water re-freezes to form massive ice particles 3. solid ice - compaction occludes posotiy btwn ice particles

Answer 54

2 subsystems 1. valley glaciers - -ice streams that flow from ountain areas down valley - -nearly 200,000 valley glaciers - -only 1-2% of all ice on earth - -confined to canyons nd valleys of mounatineous terrains - 2. continental glaciers - -huge ice sheets - cover most underlying terrain - -continent-sized ice masses - Antarctic sheet is over 4500 m thick - -ice sheets include 95% of all glacier ice - -glacial ice accounts for 2.14% of all water on earth - -77.4% of fresh water

Answer 55

glaciers move by the slow deformation of the ice by an increase in pressure from the overlying ice 1. shifting and rotation of grains of ice 2. pressure melting lubricates ice (melting and freezing) 3. internal slipping - displacement along slip lines movement of ice is dependent ons low accumulation and slope - -accumulate is greatest at glacier head - -gravity pulls ice downard and outward - -flows upward towards the snout 1. sediment input-subglacial erosion (Accumulation area - input by precipitation) 2. zone of transportation - sum evaporates and others melt towards sediment output

Answer 56

- -water (ice) moves through the open glacial system - -at EQ, input = output, mass balance - -if input > output, glacier expands - -if input < output, glacier shrinks temp and precipitation are the major variables ice is brittle - -differential flow velocity creates tesntsional stress - -may occur in any zone - -crevasses form as a result of differential flow - generally form at right angle to flow

Answer 57

ice wedging tends to smooth surface - -plucing up loose fragments - -ground-upi rock abrades the surface - -glacial striations form parallel to the direction of ice flow at glacier terminus: - -sediment is deposited as terminal moraines - -recessional moraines indicate periods of stability - -meltwater arries away and re-works sediments in outwash plains - -wind may deposit "rock flour" in the form of glacial loess TILL - unsorted glacial sediment STRATIFIED DRIFT - water re-worked glacial sediment

Answer 58

valley glaciers are repsonsibily for the most rugged and scenic mountain terrain on earth (Alps, Sierra nevadas, Himalayas, Rockies) - shapes and peaks made by eroded ice 1. straighten 2. deepen 3. widen the valleys they flow through glaciers produce unique geomorphic features 1. U shaped valleys 2. horns - -sharp peak bounded by 3 or more cirques - -where 2 or more cirques approach summit crest they sculpt mountain crest to form a pyramid shaped peak 3. haging valley - -characteristic U shape valley of a smaller glacier 4. truncated spur 5. cirques - -head of glacier is enlarged b pluckng and grows headward toward the mountain crest to form cirque 6. arete - -a sharp crested ridge bounded by 2 cirques` - -rounded topography developed by steam erosion produce sharp, angular crests and divides called aret`

Answer 59

lobal event that disrupted hydrologic cycle - -began 2-3M years ago - -ice began retreated 15-20,000 ya - -4 major periods of glaciation - ->100 M drop in sea level severe climate change shifted ecoogy - -plants died and animals migrated - -species displaced about 3200 - -numerous extinctions - especially large mammals (ice age) BEFORE --pre-glacial drainge of NA was NE through Canada AFTER --glaciation produced the Mississippi-Missouri-Ohio river system glacial erratic - boulder of Precamrian Sioux Quartzite (from Canada) forming the Great Lakes - Michigan, Wisconsin, Minnesota one of the most imp. effects of Plestocene glaciation was the repeated worldwide rise and fall of sea level - retreat and advance of glaciers --ASIA WAS CONNECTED TO NORTH AMERICA BY LAND BRIDGE called BERING STRAIT - and Britain was connected to Europe

Answer 60

Isostatic adjustment - -Ice shees caused depression of lithosphere - -continents may be depressed below sea level - -cont. to rebound post glaciation - -rebound rates of up to 3.5 cm/yr still occur this was caused by the weight of ice - depressed the continents --triggeres some large earthquakes in Scandinavia

Answer 61

Rain fed lakes developed in arid/semi-arid regions - --formed in isolated basins - -evidence by remaining shorelines and features and salt flats - -Lake Bonneville ---> Great Salt Lake sea level change - repeated rise and fall of sea level during glacial and interglacial periods - --ice trapped huged quantities of water - -Antarctic sheet contains enough water to raise sea level -- approx. 70 M - -coastline used to be wayyy wider...it is now covered in water that melted

Answer 62

causes for climate shift are not well known - -glaciation is an unusual event - -earth's climate has generally been milder than today - -high precipitation rates are needed for glacial growth causes for climate change may include: - -solar output not constant - -Milankovitch cycles - earth's orbit and axis tilt - -changes in atmospheric composition - -position of continents and ocean circulation ICE AGES are rare!! --ice age is coming... 15000 years to 50000 years (Dependent on co2 levels)

Answer 63

systems of flowing ice that form where more snow accumualtes each year than melts --ice flow erodes the surface of land by abrasion and plucking - sediment is transported by glacier and depostied where the ice melts - modifies the landscape major impact of ice age is glacial erosion, modification of drainage systems, creation of numerous lakes, fall of sea level, isostatic adjustments of lithosephere, and migration and selective extinction of plant and animal species

Answer 64

zone of ablation - is where ice leaves the system by melting, evaporating and calving - melting is the major process invlunced by cloud cover, air temp., rain dust and dirt - -creates meltwater at the end of glacier and over its whole surface - when it is abundant, it goes int ocrevasses and pore spaces btwn ice grains and creates a zone of saturation within glacier - -water table is then created in glacier and can be seen a few meters below surface of crevasses calving occurs where glacier enters sea and is broken into large fragments that float away as icebergs and melt - most of ice on entire Antarctic continent reaches sea - some extends over arctic glaciers as huge icebergs break away from shores and float north

Answer 65

glaciers erode by plucking or abrasion 1. plucking - lifting out and removal of fragments of bedrock by the moving ice ==oe of the most effective ways glacier erodes the land --involves ice wedging - meltwater seeps into joints or fractures, expands and freezes which wedges loose blocks of rock - most effective in areas where bedrock has lots of joitns and cracks 2. abrasion - -filing process - angular blocks plucled and quarried by the moving ice freeze firmly into glacier - become groun over which glacier moves - -then similar to snadpaper, - -trademark process of glaciers bc wind, rivers and waves do not have ability tog rasp and use rock fragments - -abraded as they grind against bedrock surface valley glaciers forming moraines - -end moraine - ice leaves system through melting and evaporation and load is deposited here - -terminal moraine - extends in a braod arc, conforming to the shape of the terminus of the ice - traps meltwater and forms a temporary lake - -recessional moraine - forms during periods of stabilization when ice recedes = forms behind terminal moraine

Answer 66

flowing of ice removes soil and erodes several meters of underlying bedrock - material is transported long distances and deposited near ice margins - creates moraines, drumlines, eskers, kettles, lake sediment and outwash plains 1. debris (till) - transported by glacier accumulates at te hice margin as a terminal moraine 2. ground moraine - beneath ice is variable thickness of till, transported by glacier and deposited as ground moraine 3. esker - streams of metlwater flow in tunnels and beneath ice and carry large bed load - deposited to form a long ridge called esker 4. varves - depostis on the lake bottom are stratigied in a series of alternating light and dark layers called varies - -light accumulates during summer/spring and dark in winter 5. kettle - ice blocks left behind glacier front are partly buried in outwash plain or moraines - when an isolated blokc of drebis-covered ice melts, a depression called kettle is formed 6. erratices - scattedered across the surface of glaciated regions in N Am. and Europe are large fields of boulders

Answer 67

composition of sea water - -dominated by NACL (30g NaCL, 3.5% salt) - -comes from chemical weathering of rocks and volcanic gasses

Answer 68

wind impacts the surface layer - -prevailing winds push water in one direction - -water is deflected by land - -form roughly circular patterns density driven currents - -thermohaline circulation - -Temp. and salinity control density of sea water - -cold water > warm water - -high salinity > low salinity - -1000 years

Answer 69

coriolis force causes surface currents to turn - -surface water may move away from a coastline - -cold, deepwater rises to replace it - -EL NINO the coriolis effect plus frictional copling of wind and water (Ekman transport) cause net movement of surface water at bout 90 degrees to the right of hte wind direction in N hemisphere and to the left of wind direction in S hemisphere - -Ekman transport moves surface wayers away from coast, surface waters are replaced by water that wells up from below in process known as upwelling - -when Ekman transport moves surface waters toward coast, water piles up and sinks in process known as downwelling

Answer 70

caused by gravitational attraction of earth and moon - -tidal range may vary from barely noticeable to more than 20 m - -some of wind's energy is transferred to the water surface - wave height, length, and speed are controlled by wind speed, duration and dutch CREST = high point of wave TROUGH = low point of wave WAVE HEIGHT = vertical distance btwn crest and trough WAVE LENGTH- horizontal distance btwn 2 crests WAVE BASE = 1/2 wave length

Answer 71

a particle of water moves in an orbit - a nearly circular path as the wave passes --as waves move from deep water to shallow water, they begin to be affected by the ocean bottom as the wave drage the sloping bottom wedged the wave up, increasing the wave height - the unstable wave eventually breaks wave refraction: as waves arrive at an angle to the shore, the wave botom drage the floor and they break progressively waves DO NOT strike the shore exactly parallel --the movement of sediment parallel to shore when waves strike the shoreline at an angle

Answer 72

eventually the sand being moved by longshore drife is deposited - forming a SPIT beach is a river of sand - trapping sand starved the beach down the coast "Coastal straightening" - energyis concentrated on headlands rip current normal cusps distinguishable by discoloration and sea foam - flow along the surface and die out at depth

Answer 73

a strip of sand or gravel that extends from the low-water line inland to a cliff or permanent vegetation plate tectonics - -erosional coasts - -depositional coasts - drowned coasts - -coasts shaped by organisms rocky coasts are found in areas of high wave energy --most beach sediment is quartz sand and is resistant to chemical weathering

Answer 74

reefs - Bahamas atolls - watching a volcano die winter beach is narrow - -waves are larger - -beach is eroded - -sand stored offshore summer beach is wide - -waves are smaller - -beach builds out - -bar is eroded what happens if we interfere with process? - ex. in palm beach inlet in Florida - led to coastal problems GROINS are constructed to hold sand on beach (piers) --breakwater are "intended" to create a safe-harbor

Answer 75

where does it come from? - -rivers (most common source) - -glaciers - -reefs - -artifician (beach nourishment/resoration)

Answer 76

- -wind blowing over sea forms waves - -water motion in a wave is orbital - -waves spend their energy on the beach - -beaches are moving towards equilibrium - -most beach sand it from rivers - -4 variable types of coasts have diff. traits - -beaches/coasts are highly dynamic

Answer 77

- -wind generated waves provide most of the energy for shorelines proceses - -wave refraction concentrates energy on headlands and disperses it in bays erosion and deposition along a coast develop a straight or gently curving shoreline that is in equilibrium with the energy expended upon it reefs grow in tropical climates and thrive only in shallow, clear marine waters, - fringing reefs around volcanic islands can evolve into atolls tides are produced by gravitational attraction of moon and locally exert a major influence on shorelines tsunamis are waves generated by EARTHQUAKES, volcanic eruptions, and subaqueous landslides that disturb sea floor

Answer 78

one of most imp. shoreline processes - generated by waves advancing obliquely toward the shore -transports sediment parallels to the coast ---sediment transported by waves and longshore current is deposited in areas of low energy to form beaches, spits and barrier islands generated as waves strike the shore at an agle - as waves strike shore at 90 degrees, water and sedimet moved by breaker are transported obliquely up beach in direction of wave's advance - when wave's energy is spent, water and sedimet return with backwash directly down beach - -so a single grain of sand is moved in a series of small steps up shore, then returned to beach slope - so it moves in a net transport parallel to shore - process called BEACH DRIFT - -longshore current develops in the breaker zone drift results in the movement of an enermous amount of sediment - moved by action of beach drift - -if wave direction is constant, longshore drift ocurs in one direction only - -if waves approach shore at diff. angles during diff. seasons, longshore drift is reversed

Answer 79

breaker - wave crest extends beyond support range of underlying column of water and the wave collapses/breaks - all the water in the column moves forward, releasing energy as a wall of movng, turbulent surf called the BREAKER swash - after breaker collapses, the swash (turbulent sheet of water) flows up the beach slope - powerful surge that causes landward movement of sand and gravel on beach backwash - water flows down beach slope as backwash, although some seeps into the permeable sand and gravel wae refraction - key factor in shorelines processes bc it finluences the distribution of energy along the shore as well as direction in whcih coastal water and sediment move --occurs bc the part of wave in shallow water behings to drag the boomw and slows, whereas the segments of the same wave in deeper water move forward at normal velocity - makes a bent, refracted wave so crest line tends to become parallel to shore as wave approaches shore...the wave lenght decreases dramatically

Answer 80

abrasive action of sand and gravel moved by waves and currents --sea cliff or wave-cut cliff - creates a saw in bedrock - ulitametly collapses - where the fallen debris is broken up ad removed by wave action - process is repeated on fresh surface of new cliff space wave-cut platform - produced at base wave-built terrace - sediment from erosion of cliff is transported by longshore drift and depostied in deeper water to form this hanging valleys --stream valleys that formerly reached the coast at sea level are shortened and left as hanging valleys erosion in zones of weakness 1. --sea caves - hollows out the rock and may become a cave 2. sea arches - -bc headland commonly is subjected to erosion on both sides..can create an arch in the sea 3. sea stack - when the arch collapses - only a small pinnacle is left in the ocean (happens in that order - 1,2,3)

Answer 81

sediment is transported in areas of low wave energy to form new land 1. beaches - short bulid of unconsolidated sediment -sand is most common material - some are cobbles and boulders 2. spits - areas where sraigth shorelines is indented by bays or estuaries - longshore drift extends the beach from mainland and forms a spit - -if extends completely across front of bay called baymouth bar 3. tombolos - -beach despostis that grow outward and connect the shore with an offshore island 4. barrier islands - long offshore islands of sediment parallel to s shore eroding from spread out system of bays and islands to eventually producing a smooth coastline at equilibrium

Answer 82

storm surges - expend tremendous amts. of energy along coastal regions and prdocue damage and rapid changes in coastal morpholofy --intesne storms like hurricanes and typhoons are centered around low pressure systems in atmospere that cause sea surface to rise in a broad dome while the depress surface further away tsunamis - movement of floor by earthquake, volcanic eruption or submarine landslide produces - -long wavelength and travels acoss ocean at high speeds - near shore the wave length decreases and height increases - -Japanese term - -originate far from shore - most occur in pacific ocean bc has a series of active colcanoes and intense seismicity - -Tohoko earthquake in Japan created tsunami as much as 6 M high when struck isaland - -tsunamis also have crest and trough - -first sign that a tsunami is coming is not an immense wall fo water but the sudden withdrawal of the sea

Answer 83

unique type of coastal feature bc biological in origin - complex community of corals, algae, sponges and other marine invertebrates --most reefs grow and thrive only in warm, shalow water of semitropical and tropical regions 1. fringing reefs - (.5-1km wide)attached to land masses as shores of volcanic islands or continents - corals grow seaward toward food supply - -need sunlight to grow so usually absent near deltas and mouths of rivers where there is muddy water 2. barrier reefs - -separated from mainland by a lagoon - 20+ km wide - barrier reefs of islands in south Pacific are marked by zone of white breakers - at intervals, narrow gaps occur which excess shore and tidal water can exit - Great Barrier Reef in Australia 3. platform reefs - grow in isolated oval patches in warm shallow water on continental shelf 4. atolls - roughly circular reefs that rise from deep water enclosing a shallow lagoon - -outer marine is naturally the side of most vigorous coral growth

Answer 84

produced by gravitational attraction of the moon and earth - -affect coasts in 2 ways 1. initiating a rise and fall of water level 2. generating tidal currents tides - when sea advances and retreats in a regular rhythm twice in approx. 24 hours

Answer 85

precipitation < evaporation (precipitation less than 25 cm/yr - -T varies from very hot to very cold - -slow rates of weathering - -erosion by wind - -evaporite deposits low rainfall produces -no perennial streams - dry soil - little vegetation - high evaporation cold dry ocean currents polar deserts - regions N and S of 66 degrees latitude

Answer 86

water erosion - flash floods wind erosion - -wind carries sediment - -no plant cover protection - -wind is NOT as effective at moving sand as is water - suspended load wind blowing past. grain creates: - -LIFT - formation of a zone of low pressur around a grain - -DRAG - impact of air molecules on the grain grains move a variaty of ways (depends on particle size and wind velocity) 1. saltation 2. creep 3. suspension - -in the air

Answer 87

lag deposit - -blowing away small particles - larger particles remain (Desert pavement) - -takes place in the absense of vegetation abrasion - -natural sandblasing - -energy of wind is transferred to wind-driven particles - -particles impact rock surface and knock off small pieces - -most effectie on poorly consolidated sediments VENTIFACTS - abraded and plished rock surface YARDANGS --elongated, streamlines ridges (Egypt)

Answer 88

deflation - -may excavate blowouts - -only limit is ht depth of the groundwater - -oasis suspension - -silt and clay particles - carried high in the atmosphere - -transported long distances - -dust from sahara may reach the Caribbean (Death of a reef)

Answer 89

sand sheets - -sand sheets occur in areas of lower wind velocity and larger grain size - -grains are too large to move by saltation - -moving portion of sheet is a few cm thick leads to TALUS PLAYAS ALLUVIAL FAN

Answer 90

a hill or ridge of sand deposited by wind - -air flow is disrupted - -pocket of low wind velocity is formed - -sediment collects in the pocket - -growing dune further disruprs air flow dune geometry - -asymmerical - -shallow upwind slope - meaning sand moves up the shallow slope in the direction of wind - -steep downwind slope (angle of repose), then sand slumps down the face on steep side - -sand is transported up the windward face by saltation and surface creep, acumulates at crest - -crest becomes unstable, sand avalanches down the slip face (Cross bedding)

Answer 91

Barhan dunes - -Isolated, crescent shaped dunes with horns pointing downwind - -Develop in areas of limited available sand with moderate winds from one direction trasnverse dunes - -Similar environment to Barchan dunes - -Greater availability of sand longitudinal dunes - -Develop in areas of limited available sand with strong, bi-directional winds - -Form evenly spaced ridges star dunes - -Isolated sand hill with pyramidal form - -Formed in areas with no single prevailing wind direction parabolic dunes - -A “U” or “V” shaped dune with long trailing arms - -Common in coastal areas with abundant sand, and prevailing ocean winds - -Migrate landward - -Typically vegetated

Answer 92

Loess – thick deposits of wind blown dust - -Dominated by silt size grains - -Transported long distances desertification - -Deserts are formed by natural changes - -Transitional - Shrink & expand over time - -desertification is the loss of farmable land on the margins of deserts - can be caused by human activity or slight climtic fluctuations causes of desertification in semiarid regions (human activity) --overgrazing, cultivation, poor irrigation, destruction of vegetation

Answer 93

Great Sand dunes national monument in Colorado --eolian system takes it energy from the sun an uneven heating of the planet - fluid that flows readily - picks up and transports huge volumes of sediment 1. wind is NOT an effective agent in eroding the landscape - but can produce deflation basins and yardangs as well as pits and grooves in rocks 2. major result of wind activity is transportation of loose, unconsolidated fragments of sand and dust - transports sad by saltation and surface creep - dust is transported in suspension 3. sand dunes migrate as sand grains are blown up and over windward and accunulate on a slope 4. various types form depending on wind velocity, sand supply and constancy of wind direction wind blown dust is LEOSS and it form sblanket deposits - to mask older landscape beneath it - source of leoss is desert dust or fine rock debris deposited by glaciers

Answer 94

1. deflation - -most significant type of wind erosion - process in which loose particles of sand and dust are lifted from the surface and blown away - -turbulence of wind is able to lift these fine materials - -commonly occurs in semiarid regions - -resul tis shallow depressions called delfation basins - -most comon is the Great Plains in Colorado, Kansas and Texas - -wind can only move sand and dust-particles - so deflatoin leaves concentrations of coarser material called lag deposits or desert pavements 2. abrasion - -similar to articifial sand blasting used to clean building stones - -gets energy from kinetic energy of wins - grains impact rock surfaces and small particles are knocked off the rock - some effects of wind abrasion are seen on the surface of bedrock - -VENTIFACTS are pebbled "wind made" that are shaped and polished by the wind - -YARDANGS are less common but are larger lanldforms produced by wind abrasion with distinctive linear ridges

Answer 95

sand - -moves by lift - causedby air flowing over grain - sucked into air flow - -drag - causedby impact of air molecules on grains surface - -saltation - results from impact and elasti bounce- grain falls to surface and collides with other grains - impact causses one or more grains to bounds into the air - friven forward by drsag of stronger wind - -also CREEP - some grains are too large to be ejected into flowing air so they move by surface creep (rolling and sliding) - large grains are moved by impact of saltating grains and drag of wind dust - -suspension - small grains of dust are carried by turbulence in wind flow - -lifted high into atmosphere and carried great distance before come back to earth depsosited as sand sheets or dunes

Exam 2 Flashcards

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