Presentation on theme: "EARTH SCIENCE Geology, the Environment and the Universe"— Presentation transcript:
1 EARTH SCIENCE Geology, the Environment and the Universe Chapter 8: Mass Movements, Wind, and Glaciers
2 Section 8.1 Mass Movements Section 8.2 Wind Section 8.3 Glaciers CHAPTER8Table Of ContentsSection 8.1 Mass MovementsSection 8.2 WindSection 8.3 GlaciersClick a hyperlink to view the corresponding slides.Exit
3 Mass Movements Essential Questions SECTION8.1Mass MovementsEssential QuestionsWhat is the relationship between gravity and mass movements?What factors affect mass movements?What are the different types of mass movements and how are they described?How do mass movements affect people?
4 Mass Movements Review Vocabulary SECTION8.1Mass MovementsMass movements alter Earth’s surface over time due to gravity moving sediment and rocks downslope.Review Vocabularygravity: the force every object exerts on every other object due to their masses
5 Mass Movements New Vocabulary mass movement creep mudflow landslide SECTION8.1Mass MovementsNew Vocabularymass movementcreepmudflowlandslideslumpavalanche
6 Mass Movements Mass Movements SECTION8.1Mass MovementsMass MovementsThe downslope movement of soil and weathered rock resulting from the force of gravity is called mass movement.Because climate has a major effect on the weathering activities that occur in a particular area, climatic conditions determine the extent of mass movement.
7 Mass Movements Mass Movements SECTION8.1Mass MovementsMass MovementsAll mass movements occur on slopes. Because few places on Earth are completely flat, almost all of Earth’s surface undergoes some degree of mass movement.
8 Factors that Influence Mass Movements SECTION8.1Mass MovementsFactors that Influence Mass MovementsSeveral factors influence the mass movements of Earth’s material: the material’s weight, the material’s resistance to sliding or flowing, triggers that shake material loose, and the presence of water.
9 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsCreepThe slow, steady, downhill flow of loose, weathered Earth materials, especially soils, is called creep.The effects of creep are usually noticeable only over long periods of time.
10 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsCreepOne way to way to tell whether creep has occurred is to observe the positions of structures and objects.
11 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsFlowsEarth flows are moderately slow movements of soils, whereas mudflows are swiftly moving mixtures of mud and water.
12 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsMudflows12
13 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsMudflows13
14 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsMudflows14
15 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsFlowsMudflows are also common in sloped, semi-arid regions that experience intense, short-lived rainstorms.
16 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsFlowsMudflows can be triggered by earthquakes or similar vibrations.Lahars are mudflows that occur in volcanic regions where the heat from a volcano melts snow on nearby slopes that have fine sediment and little vegetation.
17 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsLahar - Flows17
18 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsLahar - Flows18
19 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsLahar - Flows19
20 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsLahar - Flows– pic 2 in New Zealand20
21 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesA rapid, downslope movement of Earth materials that occurs when a relatively thin block of soil, rock, and debris separates from the underlying bedrock is called a landslide.
22 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesLandslides are common on steep slopes, especially when soils and weathered bedrock are fully saturated by water.A rockslide is a type of landslide that occurs when a sheet of rock moves downhill on a sliding surface. Rockslides are often triggered by earthquakes.
23 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesLandslides23
24 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesLandslides24
25 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesrockslides25
26 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesrockslides26
27 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesWhen the mass of material in a landslide moves along a curved surface, a slump results.Material at the top of the slump moves downhill, and slightly inward, while the material at the bottom of the slump moves outward.
28 Mass Movements Please click the image above to view the video. SECTION8.1Mass MovementsPlease click the image above to view the video.
30 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsSlidesLandslides that occur in mountainous areas with thick accumulations of snow are called avalanches.Avalanches occur when snow that falls on an icy crust builds up, becomes heavy, slips off, and slides downslope.
31 Types of Mass Movements SECTION8.1Mass MovementsTypes of Mass MovementsRockfallsOn high cliffs, rocks that are loosened by physical weathering processes or by plant growth can break up and fall directly downward. Rockfalls commonly occur at high elevations, in steep road cuts, and on rocky shorelines.
32 Mass Movements Affect People SECTION8.1Mass MovementsMass Movements Affect PeopleHuman activities such as construction of buildings, roads, and other structures can make slopes unstable, contributing to the factors that cause mass movements.
33 Mass Movements Affect People SECTION8.1Mass MovementsMass Movements Affect PeopleReducing the risksThe best way to reduce the number of disasters related to mass movements is to educate people about the problems of building on steep slopes.
34 SECTION8.1Section CheckBy adhering to sediment grains and rock layers, water reduces the risk of landslides.a. trueb. false
35 The effects of gravity increase with the steepness of the slope. SECTION8.1Section CheckThe effects of gravity increase with the steepness of the slope.a. trueb. false
36 SECTION8.1Section CheckIn which type of mass movement does a section of rock or sediment move downhill along a curved surface?a. rockslideb. rockfallc. slumpd. mudflow
38 Wind Essential Questions SECTION8.2WindEssential QuestionsWhat are the conditions that contribute to the likelihood that an area will experience wind erosion ?What features are characteristic of wind erosion and deposition ?How do dunes form and migrate ?
39 Wind Review Vocabulary SECTION8.2WindWind modifies landscapes in all areas of the world by transporting sediment.Review Vocabularyvelocity: the speed of an object and its direction of motion
41 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportLimited precipitation leads to an increase in the amount of wind erosion because precipitation holds down sediments and allows plants to grow.
42 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportWind transport and erosion primarily occur in areas with little vegetative cover, such as deserts, semiarid areas, seashores, and some lakeshores.
43 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportDeflationThe lowering of the land surface that results from the wind’s removal of surface particles is called deflation.
44 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportDeflationDuring the 1930s, portions of the Great Plains region experienced severe drought. Because large areas of natural vegetation had been removed, strong winds readily picked up the dry surface particles. The region became known as the Dust Bowl.
45 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportAbrasionAnother process of erosion, called abrasion, occurs when particles such as sand rub against the surface of rocks or other materials.
46 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportAbrasionBecause sand is often made of quartz, a hard mineral, wind abrasion can be an effective agent of erosion—windblown sand particles eventually wear away rocks.
47 Wind Erosion and Transport SECTION8.2WindWind Erosion and TransportAbrasionRocks shaped by windblown sediments are called ventifacts.
48 Wind Wind Deposition Dunes SECTION8.2WindWind DepositionDunesIn windblown environments, sand particles tend to accumulate where an object, such as a rock, landform, or piece of vegetation, blocks the forward movement of the particles. Over time, the pile of windblown sand develops into a dune.
49 Wind Wind Deposition Dunes SECTION8.2WindWind DepositionDunesThe conditions under which a dune forms determine its shape and include the availability of sand, wind velocity, wind direction, and the amount of vegetation present.
50 Wind Wind Deposition Dunes SECTION8.2WindWind DepositionDunesDune migration is caused when prevailing winds continue to move sand from the windward side of a dune to its leeward side, causing the dune to move slowly over time.
51 Wind Please click the image above to view the interactive table. SECTION8.2WindPlease click the image above to view the interactive table.
52 Wind Wind Deposition Loess SECTION8.2WindWind DepositionLoessThick, windblown silt deposits are known as loess.Loess soils are some of the most fertile soils because they contain abundant minerals and nutrients.Check audio. Should sound like luss.
53 Wind Wind Deposition Loess SECTION8.2WindWind DepositionLoessThis map shows the location of loess deposits in the continental United States.
54 SECTION8.2Section CheckMost of the sand that is blown by wind moves along the ground with a bouncing motion.a. trueb. false
55 Which feature forms as a result of deflation? SECTION8.2Section CheckWhich feature forms as a result of deflation?a. dunesb. blowoutsc. ventifactsd. pillars
56 How do sand dunes migrate? SECTION8.2Section CheckHow do sand dunes migrate?Possible answer: Sand that is blown by wind from the windward side of the dune accumulates at the crest until it is carried down the leeward side. As long as the wind blows, this process continues, moving sand from one side of the dune to the other and causing the dune to advance.
58 Glaciers Essential Questions How do glaciers form? SECTION8.3GlaciersEssential QuestionsHow do glaciers form?What are the similarities and differences between valley glaciers and continental glaciers?How do glaciers modify landscapes?What features are characteristic of glacial erosion and deposition?
59 Glaciers Review Vocabulary SECTION8.3GlaciersGlaciers modify landscapes by eroding and depositing rocks.Review Vocabularylatitude: distance in degrees north and south of the equator
60 Glaciers New Vocabulary glacier outwash plain valley glacier drumlin SECTION8.3GlaciersNew Vocabularyglaciervalley glaciercontinental glaciercirquemoraineoutwash plaindrumlineskerkamekettle
61 Glaciers Moving Masses of Ice SECTION8.3GlaciersMoving Masses of IceA large mass of moving ice is called a glacier.Glaciers form near Earth’s poles and in mountainous areas at high elevations. They cover about 10 percent of Earth’s surface.Map of glaciers around the world. Glaciers cover roughly 10 percent of Earth's land area. A vast majority of that, 90 percent, overlies the continent of Antarctica . Read more:
62 Glaciers Moving Masses of Ice Valley glaciers SECTION8.3GlaciersMoving Masses of IceValley glaciersGlaciers that form in valleys in high, mountainous areas are called valley glaciers.As valley glaciers flow downslope, they carve V-shaped stream valleys into U-shaped glacial valleys.
63 Valley Glaciers Bylot Island, Canada Bylot Island, Canada
64 Glaciers Moving Masses of Ice Continental glaciers SECTION8.3GlaciersMoving Masses of IceContinental glaciersGlaciers that cover broad, continent-sized areas are called continental glaciers.These glaciers form in cold climates where snow accumulates over many years.
65 Glaciers Moving Masses of Ice Glacial movement SECTION8.3GlaciersMoving Masses of IceGlacial movementBoth valley glaciers and continental glaciers move outward when snow gathers at the zone of accumulation, a location in which more snow falls than melts, evaporates, or sublimates.
66 Glaciers Glacial Erosion SECTION8.3GlaciersGlacial ErosionOf all the erosional agents, glaciers are the most powerful because of their great size and weight.
67 Glaciers Glacial Erosion SECTION8.3GlaciersGlacial ErosionWhen a valley glacier moves, it breaks off pieces of rock through a process called plucking.When glaciers with embedded rocks move over bedrock, they act like grains on a piece of sandpaper, grinding parallel scratches into the bedrock.
68 Glaciers Glacial Erosion SECTION8.3GlaciersGlacial ErosionAt the high elevations where snow accumulates, valley glaciers scoop out deep, bowl-shaped depressions, called cirques.
69 Glaciers Glacial Erosion SECTION8.3GlaciersGlacial ErosionWhen there are glaciers on three or more sides of a mountaintop, the carving action creates a steep, pyramid-shaped peak, called a horn.
70 Glaciers Glacial Erosion SECTION8.3GlaciersGlacial ErosionHanging valleys are formed by valley glaciers when higher tributary glaciers converge with the lower primary glaciers and later retreat. A valley is left hanging high above the primary valley floor.
71 Glaciers Glacial Deposition SECTION8.3GlaciersGlacial DepositionGlacial till is the unsorted rock, gravel, sand, and clay that glaciers carry embedded in their ice and on their tops, sides, and front edges.Glaciers deposit unsorted ridges of till called moraines when the glacier retreats.
72 Glaciers Glacial Deposition Outwash SECTION8.3GlaciersGlacial DepositionOutwashWhen the farthest ends of a glacier melt, meltwater floods the valley below. Outwash is the gravel, sand, and fine silt sediment that is deposited by meltwater carried away from the glacier.
73 Glaciers Glacial Deposition Outwash SECTION8.3GlaciersGlacial DepositionOutwashThe area at the leading edge of a glacier where meltwater flows and deposits outwash is called an outwash plain.
74 Glaciers Glacial Deposition Drumlins, eskers, and kames SECTION8.3GlaciersGlacial DepositionDrumlins, eskers, and kamesContinental glaciers that move over older moraines form the material into elongated landforms called drumlins.
75 Glaciers Glacial Deposition Drumlins, eskers, and kames SECTION8.3GlaciersGlacial DepositionDrumlins, eskers, and kamesStreams flowing under melting glaciers leave long, winding ridges of layered sediments called eskers.A kame is a mound of layered sediment that forms when till gets washed into depressions or openings in the melting ice.
76 Visualizing Continental Glacial Features SECTION8.3GlaciersVisualizing Continental Glacial FeaturesContinental glaciers carve out vast regions of landscape, leaving behind distinctive features such as kames, eskers, drumlins, and moraines.
77 SECTION8.3GlaciersPlease click the image above to view the video.
78 Glaciers Glacial Deposition Glacial lakes SECTION8.3GlaciersGlacial DepositionGlacial lakesKettles, or kettle lakes, form when water from runoff or precipitation fills a hole that formed when a large block of ice broke off a continental glacier and melted.
79 Glaciers Glacial Deposition Glacial lakes SECTION8.3GlaciersGlacial DepositionGlacial lakesWith valley glaciers, cirques can also fill with water and become cirque lakes.When a terminal moraine blocks off a valley, the valley fills with water to form a moraine-dammed lake.
80 About how much of Earth’s surface is currently covered by glaciers ? SECTION8.3Section CheckAbout how much of Earth’s surface is currently covered by glaciers ?a. 10 percentb. 20 percentc. 30 percentd. 40 percent
81 SECTION8.3Section CheckWhich glacial feature forms from sediments deposited by a stream flowing beneath a glacier?a. eskerb. cirquec. kettled. moraine
82 Which glacial feature forms as a result of deposition of sediment? SECTION8.3Section CheckWhich glacial feature forms as a result of deposition of sediment?a. hornb. arêtec. cirqued. moraine
84 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersResourcesEarth Science OnlineStudy GuideChapter Assessment QuestionsStandardized Test PracticeClick on a hyperlink to view the corresponding feature.
85 SECTION8.1Mass MovementsStudy GuideMass movements alter Earth’s surface over time due to gravity moving sediment and rocks downslope.Mass movements are classified in part by how rapidly they occur.
86 SECTION8.1Mass MovementsStudy GuideFactors involved in the mass movement of Earth materials include the material’s weight, its resistance to sliding, the trigger, and the presence of water.Mass movements are natural processes that can affect human life and activities.Human activities can increase the potential for the occurrence of mass movements.
87 SECTION8.2WindStudy GuideWind modifies landscapes in all areas of the world by transporting sediment.Wind is a powerful agent of erosion.Wind can transport sediment in several ways, including suspension and saltation.
88 SECTION8.2WindStudy GuideDunes form when wind velocity slows down and windblown sand is deposited.Dunes migrate as long as winds continue to blow.
89 Glaciers Glaciers modify landscapes by eroding and depositing rocks. SECTION8.3GlaciersStudy GuideGlaciers modify landscapes by eroding and depositing rocks.Glaciers are large moving masses of ice that form near Earth’s poles and in mountain areas.Glaciers can be classified as valley glaciers or continental glaciers.
90 Glaciers Glaciers modify the landscape by erosion and deposition. SECTION8.3GlaciersStudy GuideGlaciers modify the landscape by erosion and deposition.Features formed by glaciers include U-shaped valleys, hanging valleys, moraines, drumlins, and kettles.
91 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersChapter AssessmentWhich sediment grain size is most abundant in loess?a. clayb. siltc. sandd. gravel
92 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersChapter AssessmentWhich observation provides evidence that material has moved by the process of creep?a. scattered large bouldersb. steep scarps in hillsc. tilted trees or postsd. piles of rock talus
93 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersChapter AssessmentBy what agent is glacial outwash deposited?a. iceb. windc. waterd. gravity
94 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersChapter AssessmentWhat is a lahar?Answer: A lahar is a mudflow that forms on a volcano, often just after an eruption. The presence of loose volcanic ash and snow that can melt rapidly contributes to conditions favorable for the formation of lahars.
95 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersChapter AssessmentHow do valley glaciers and continental glaciers differ?Possible answer: Valley glaciers form in mountains at high altitudes and are comparatively small. Continental glaciers are much larger and form at high latitudes. Continental glaciers have, however, extended into midlatitudes during ice ages.
96 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersStandardized Test PracticeWhich landmass has the most glacier ice?a. Greenlandb. North Americac. South Americad. Antarctica
97 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersStandardized Test PracticeWhich type of sand dune has a horseshoe shape with arms that point downwind?a. transverseb. barchanc. parabolicd. longitudinal
98 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersStandardized Test PracticeBy which process does a ventifact form?a. abrasion by windblown sandb. erosion of kame gravelc. tumbling in a landslided. scraping beneath a glacier
99 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersStandardized Test PracticeHow does a kettle lake form?Answer: As a glacier recedes, blocks of glacier ice are sometimes left in front of the receding ice margin. When an ice block melts, a depression remains. A kettle lake forms if the depression remains filled with water.
100 Mass Movements, Wind, and Glaciers CHAPTER8Mass Movements, Wind, and GlaciersStandardized Test PracticeFlows and slides are basic types of mass movements. How is a flow different from a slide?Possible answer: A flow moves like a liquid. Some flows are stiff and move relatively slowly; others are thin and flow like water. A slide is a mass of rock or sediment that rapidly slides over a surface of weakness. The mass sometimes breaks apart as it moves downhill.