Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 8: Mass Movements, Wind, and Glaciers EARTH SCIENCE Geology, the Environment and the Universe.

Similar presentations


Presentation on theme: "Chapter 8: Mass Movements, Wind, and Glaciers EARTH SCIENCE Geology, the Environment and the Universe."— Presentation transcript:

1 Chapter 8: Mass Movements, Wind, and Glaciers EARTH SCIENCE Geology, the Environment and the Universe

2 Section 8.1Mass MovementsMass Movements Section 8.2WindWind Section 8.3GlaciersGlaciers Exit Click a hyperlink to view the corresponding slides. CHAPTER 8 Table Of Contents

3 Essential Questions What 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? SECTION 8.1 Mass Movements

4 Review Vocabulary gravity: the force every object exerts on every other object due to their masses Mass movements alter Earths surface over time due to gravity moving sediment and rocks downslope. SECTION 8.1 Mass Movements

5 New Vocabulary mass movement creep mudflow landslide slump avalanche SECTION 8.1 Mass Movements

6 The 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. SECTION 8.1 Mass Movements

7 All mass movements occur on slopes. Because few places on Earth are completely flat, almost all of Earths surface undergoes some degree of mass movement. SECTION 8.1 Mass Movements

8 Factors that Influence Mass Movements Several factors influence the mass movements of Earths material: the materials weight, the materials resistance to sliding or flowing, triggers that shake material loose, and the presence of water. SECTION 8.1 Mass Movements

9 The 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. Types of Mass Movements Creep SECTION 8.1 Mass Movements

10 One way to way to tell whether creep has occurred is to observe the positions of structures and objects. Types of Mass Movements Creep SECTION 8.1 Mass Movements

11 Types of Mass Movements Flows Earth flows are moderately slow movements of soils, whereas mudflows are swiftly moving mixtures of mud and water. SECTION 8.1 Mass Movements

12 Types of Mass Movements Mudflows SECTION 8.1 Mass Movements

13 Types of Mass Movements Mudflows SECTION 8.1 Mass Movements

14 Types of Mass Movements Mudflows SECTION 8.1 Mass Movements

15 Types of Mass Movements Flows Mudflows are also common in sloped, semi-arid regions that experience intense, short-lived rainstorms. SECTION 8.1 Mass Movements

16 Types of Mass Movements Flows Mudflows 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. SECTION 8.1 Mass Movements

17 Types of Mass Movements Lahar - Flows SECTION 8.1 Mass Movements

18 Types of Mass Movements Lahar - Flows SECTION 8.1 Mass Movements

19 Types of Mass Movements Lahar - Flows SECTION 8.1 Mass Movements

20 Types of Mass Movements Lahar - Flows SECTION 8.1 Mass Movements

21 Types of Mass Movements Slides A 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. SECTION 8.1 Mass Movements

22 Types of Mass Movements Slides Landslides 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. SECTION 8.1 Mass Movements

23 Types of Mass Movements Slides Landslides SECTION 8.1 Mass Movements

24 Types of Mass Movements Slides Landslides SECTION 8.1 Mass Movements

25 Types of Mass Movements Slides rockslides SECTION 8.1 Mass Movements

26 Types of Mass Movements Slides rockslides SECTION 8.1 Mass Movements

27 Types of Mass Movements Slides When 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. SECTION 8.1 Mass Movements

28 Please click the image above to view the video. SECTION 8.1 Mass Movements

29 SECTION 8.1 Mass Movements slump Stop here

30 Types of Mass Movements Slides Landslides 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. SECTION 8.1 Mass Movements

31 Types of Mass Movements Rockfalls On 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. SECTION 8.1 Mass Movements

32 Mass Movements Affect People Human activities such as construction of buildings, roads, and other structures can make slopes unstable, contributing to the factors that cause mass movements. SECTION 8.1 Mass Movements

33 Mass Movements Affect People Reducing the risks The best way to reduce the number of disasters related to mass movements is to educate people about the problems of building on steep slopes. SECTION 8.1 Mass Movements

34 By adhering to sediment grains and rock layers, water reduces the risk of landslides. a. true b. false SECTION 8.1 Section Check

35 The effects of gravity increase with the steepness of the slope. a. true b. false SECTION 8.1 Section Check

36 In which type of mass movement does a section of rock or sediment move downhill along a curved surface? a. rockslide b. rockfall c. slump d. mudflow SECTION 8.1 Section Check

37

38 Essential Questions What 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 ? SECTION 8.2 Wind

39 velocity: the speed of an object and its direction of motion Review Vocabulary Wind modifies landscapes in all areas of the world by transporting sediment. SECTION 8.2 Wind

40 New Vocabulary deflation abrasion ventifact dune loess SECTION 8.2 Wind

41 Wind Erosion and Transport Limited precipitation leads to an increase in the amount of wind erosion because precipitation holds down sediments and allows plants to grow. SECTION 8.2 Wind

42 Wind Erosion and Transport Wind transport and erosion primarily occur in areas with little vegetative cover, such as deserts, semiarid areas, seashores, and some lakeshores. SECTION 8.2 Wind

43 Wind Erosion and Transport The lowering of the land surface that results from the winds removal of surface particles is called deflation. Deflation SECTION 8.2 Wind

44 Wind Erosion and Transport During 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. Deflation SECTION 8.2 Wind

45 Wind Erosion and Transport Another process of erosion, called abrasion, occurs when particles such as sand rub against the surface of rocks or other materials. Abrasion SECTION 8.2 Wind

46 Wind Erosion and Transport Because sand is often made of quartz, a hard mineral, wind abrasion can be an effective agent of erosionwindblown sand particles eventually wear away rocks. Abrasion SECTION 8.2 Wind

47 Wind Erosion and Transport Rocks shaped by windblown sediments are called ventifacts. Abrasion SECTION 8.2 Wind

48 In 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. Dunes Wind Deposition SECTION 8.2 Wind

49 Wind Deposition The 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. Dunes SECTION 8.2 Wind

50 Wind Deposition Dune 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. Dunes SECTION 8.2 Wind

51 Please click the image above to view the interactive table. SECTION 8.2 Wind

52 Wind Deposition Thick, windblown silt deposits are known as loess. Loess soils are some of the most fertile soils because they contain abundant minerals and nutrients. Loess SECTION 8.2 Wind

53 This map shows the location of loess deposits in the continental United States. Wind Deposition Loess SECTION 8.2 Wind

54 Most of the sand that is blown by wind moves along the ground with a bouncing motion. a. true b. false SECTION 8.2 Section Check

55 Which feature forms as a result of deflation? a. dunes b. blowouts c. ventifacts d. pillars SECTION 8.2 Section Check

56 How 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. SECTION 8.2 Section Check

57

58 Essential Questions How 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? SECTION 8.3 Glaciers

59 latitude: distance in degrees north and south of the equator Review Vocabulary Glaciers modify landscapes by eroding and depositing rocks. SECTION 8.3 Glaciers

60 New Vocabulary glacier valley glacier continental glacier cirque moraine outwash plain drumlin esker kame kettle SECTION 8.3 Glaciers

61 Moving Masses of Ice A large mass of moving ice is called a glacier. Glaciers form near Earths poles and in mountainous areas at high elevations. They cover about 10 percent of Earths surface. SECTION 8.3 Glaciers

62 Moving Masses of Ice Glaciers 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. Valley glaciers SECTION 8.3 Glaciers

63 Valley Glaciers Bylot Island, Canada

64 Moving Masses of Ice Glaciers that cover broad, continent-sized areas are called continental glaciers. These glaciers form in cold climates where snow accumulates over many years. Continental glaciers SECTION 8.3 Glaciers

65 Moving Masses of Ice Glacial movement Both 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. SECTION 8.3 Glaciers

66 Of all the erosional agents, glaciers are the most powerful because of their great size and weight. Glacial Erosion SECTION 8.3 Glaciers

67 When 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. Glacial Erosion SECTION 8.3 Glaciers

68 At the high elevations where snow accumulates, valley glaciers scoop out deep, bowl-shaped depressions, called cirques. Glacial Erosion SECTION 8.3 Glaciers

69 When there are glaciers on three or more sides of a mountaintop, the carving action creates a steep, pyramid-shaped peak, called a horn. Glacial Erosion SECTION 8.3 Glaciers

70 Glacial Erosion Hanging 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. SECTION 8.3 Glaciers

71 Glacial Deposition Glacial 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. SECTION 8.3 Glaciers

72 Glacial Deposition Outwash When 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. SECTION 8.3 Glaciers

73 Glacial Deposition Outwash The area at the leading edge of a glacier where meltwater flows and deposits outwash is called an outwash plain. SECTION 8.3 Glaciers

74 Glacial Deposition Drumlins, eskers, and kames Continental glaciers that move over older moraines form the material into elongated landforms called drumlins. SECTION 8.3 Glaciers

75 Glacial Deposition Drumlins, eskers, and kames Streams 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. SECTION 8.3 Glaciers

76 Visualizing Continental Glacial Features Continental glaciers carve out vast regions of landscape, leaving behind distinctive features such as kames, eskers, drumlins, and moraines. SECTION 8.3 Glaciers

77 SECTION 8.3 Glaciers Please click the image above to view the video.

78 Glacial Deposition Kettles, 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. Glacial lakes SECTION 8.3 Glaciers

79 Glacial Deposition With 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. Glacial lakes SECTION 8.3 Glaciers

80 About how much of Earths surface is currently covered by glaciers ? a. 10 percent b. 20 percent c. 30 percent d. 40 percent SECTION 8.3 Section Check

81 Which glacial feature forms from sediments deposited by a stream flowing beneath a glacier? a. esker b. cirque c. kettle d. moraine SECTION 8.3 Section Check

82 Which glacial feature forms as a result of deposition of sediment? a. horn b. arête c. cirque d. moraine SECTION 8.3 Section Check

83

84 CHAPTER 8 Mass Movements, Wind, and Glaciers Resources Chapter Assessment Questions Standardized Test Practice Click on a hyperlink to view the corresponding feature. Study Guide Earth Science Online

85 Mass movements alter Earths surface over time due to gravity moving sediment and rocks downslope. Mass movements are classified in part by how rapidly they occur. SECTION 8.1 Mass Movements Study Guide

86 Factors involved in the mass movement of Earth materials include the materials 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. SECTION 8.1 Mass Movements Study Guide

87 Wind 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. SECTION 8.2 Wind Study Guide

88 Dunes form when wind velocity slows down and windblown sand is deposited. Dunes migrate as long as winds continue to blow. SECTION 8.2 Wind Study Guide

89 Glaciers modify landscapes by eroding and depositing rocks. Glaciers are large moving masses of ice that form near Earths poles and in mountain areas. Glaciers can be classified as valley glaciers or continental glaciers. SECTION 8.3 Glaciers Study Guide

90 Glaciers modify the landscape by erosion and deposition. Features formed by glaciers include U-shaped valleys, hanging valleys, moraines, drumlins, and kettles. SECTION 8.3 Glaciers Study Guide

91 Which sediment grain size is most abundant in loess? a. clay b. silt c. sand d. gravel CHAPTER 8 Mass Movements, Wind, and Glaciers Chapter Assessment

92 Which observation provides evidence that material has moved by the process of creep? a. scattered large boulders b. steep scarps in hills c. tilted trees or posts d. piles of rock talus CHAPTER 8 Mass Movements, Wind, and Glaciers Chapter Assessment

93 By what agent is glacial outwash deposited? a. ice b. wind c. water d. gravity CHAPTER 8 Mass Movements, Wind, and Glaciers Chapter Assessment

94 What 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. CHAPTER 8 Mass Movements, Wind, and Glaciers Chapter Assessment

95 How 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. CHAPTER 8 Mass Movements, Wind, and Glaciers Chapter Assessment

96 Which landmass has the most glacier ice? a. Greenland b. North America c. South America d. Antarctica CHAPTER 8 Mass Movements, Wind, and Glaciers Standardized Test Practice

97 Which type of sand dune has a horseshoe shape with arms that point downwind? a. transverse b. barchan c. parabolic d. longitudinal CHAPTER 8 Mass Movements, Wind, and Glaciers Standardized Test Practice

98 By which process does a ventifact form? a. abrasion by windblown sand b. erosion of kame gravel c. tumbling in a landslide d. scraping beneath a glacier CHAPTER 8 Mass Movements, Wind, and Glaciers Standardized Test Practice

99 How 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. CHAPTER 8 Mass Movements, Wind, and Glaciers Standardized Test Practice

100 Flows 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. CHAPTER 8 Mass Movements, Wind, and Glaciers Standardized Test Practice

101


Download ppt "Chapter 8: Mass Movements, Wind, and Glaciers EARTH SCIENCE Geology, the Environment and the Universe."

Similar presentations


Ads by Google