Mass Movements, Wind, and Glaciers Earth Science Chapter 8

Erosion and Deposition Moving and Changing the Landscape!

Erosion and Deposition Erosion: the movement of materials from place to place by the actions of wind, waves, glaciers, gravity, and/or running water. Deposition: the laying down of sediments in a new location. Each agent of erosion/deposition will produce a variety of unique surface features. Land erosion Sand deposition

Agent One: Gravity Gravity is the force of attraction between two objects. Gravity is influenced by precipitation rates, human interactions, and gradient (steepness of slope). The effect of gravity as an agent of erosion is mass movement. All three examples occur quickly. Slide Blocks of earth move down slope landslide Flow Movement of water rich particles down slope mudslide Fall Portion of rock move down slope Rock fall

8.1 MASS MOVEMENTS Mass movement is the downward transportation of weathered materials by gravity Many types of mass movement: – Talus—rock fragments weathered from a cliff that have “fallen” due to gravity – Landslide—movement of a mass of bedrock or loose soil and rock down the slope of a hill, mountain, or cliff. Can be triggered by earthquakes or volcanoes More prone along steeper slopes Often follow heavy rains

TYPES OF LANDSLIDES Creep—slow, imperceptible movement of soil down a slope—causes poles, fence posts to lean downhill. Slump—bottom of a slope becomes unable to support the soil at the top of a slope. The bottom wears away and the top “slumps” downward. Earthflow—a mass of weathered material that has been saturated with water flows downhill. Mudflow—the rapid movement of water that contains large amounts of clay and silt. – Contain more water than earthflows – Can move over 100 km/hr – Can take out houses, trees, etc. – Often occur in dry regions when they experience extremely heavy rainfall

Agent One: Gravity Landslide LandslideLandslide

Agent One: Gravity Mudflow, Mudslide mudslidemudslide

Agent One: Gravity Creep Slow down slope movement of subsoil

Agent One: Gravity Avalanche Rapid downhill movement of snow national geo

8.2 Agent Two: Wind Wind is the movement of air due to the unequal heating of the Earth’s surface. Abrasion: The wearing away of materials through constant pounding of wind-driven sediments. Deflation: The smoothing of land caused by the scrubbing of wind- driven sediments.

Agent Three: Waves Emergent Coast

Agent Three: Waves Emergent Coastline

CHAPTER 15: GLACIERS Only about 3% of the earth’s water is freshwater and that of that 3%, about 75% is locked up in glaciers. A glacier is a large mass of compacted snow and ice that moves under the force of gravity. A glacier erodes the earth’s features in one place and redeposits those materials elsewhere. Glaciers can form anywhere in the world where there is a snow line. A snow line is the lowest elevation at which a permanent layer of snow exists in the summer.

HOW GLACIERS FORM Buried snow becomes compressed and recrystallizes into a rough, granular ice material called firn or ne’ve’. Over time, the firn thickens. The weight of the material at the top compresses the firn below turning it to solid ice. Due to the weight, the ice begins to flow downward or outward. This moving mass of snow and ice is called a glacier.

TWO TYPES OF GLACIERS Valley glaciers—moves within valley walls – Long, slow-moving, wedgelike stream of ice – Also called alpine glaciers – Exist on all continents except Australia

Continental glaciers—covers a large part of a continent – Occur in areas where all precipitation is snow. – Snow and ice build up and move outward in all directions – Can break off into chunks when it reaches the sea – Greenland glacier—size of Mexico – Antarctica glacier—bigger than U.S. and Mexico combined – A glacier that is less than square meters is called an ice cap.

GLACIAL MOVEMENT AND EROSION Some glaciers move only a few centimeters a day while others move over a meter each day. This movement erodes rock and land surfaces below the glacier—can even move boulders the size of houses

Agent Four: Glaciers Glacier is a large body of ice moving slowly down a valley slope or spreading outward over land. There are two types of glaciers- valley and continental. Continental Glacier Valley Glacier

Agent Four: Glaciers When a portion of the glacier breaks off over a body of water it is referred to as an iceberg. Only the melting of continental glaciers causes sea level rise