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DECEMBER 8, 2015 AGENTS OF EROSION. WHAT IS EROSION? Erosion is the process of weathered rocks and soil moving from one place to another Erosion moves.

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Presentation on theme: "DECEMBER 8, 2015 AGENTS OF EROSION. WHAT IS EROSION? Erosion is the process of weathered rocks and soil moving from one place to another Erosion moves."— Presentation transcript:

1 DECEMBER 8, 2015 AGENTS OF EROSION

2 WHAT IS EROSION? Erosion is the process of weathered rocks and soil moving from one place to another Erosion moves sediments- tiny pieces of broken rock or soil After erosion, deposition occurs when the pieces of sediments and soil settle on land or in water.

3 AGENTS OF EROSION There are 5 agents (or causes) of erosion: 1.Gravity 2.Moving Water 3.Glaciers 4.Waves 5.Wind

4 (1) GRAVITY Definition : the force that pulls all things towards the earth’s center Erosion begins with gravity pulling material towards the center of the earth Mass Movement is the downhill movement of weathered materials caused by gravity

5 WHAT DOES GRAVITY CREATE? Mass movement, caused by gravity, can create: 1. Mudflows - water, rock, and soil mixed together that moves downhill 2. Landslides - when rock and soil slide quickly down a steep slope 3. Slumps - a mass of rock and soil suddenly slips down a slope in one large piece 4. Creep - slow downhill movement of rock and soil

6 (2) MOVING WATER Why it matters: Moving water has shaped more of the earth’s surface than any other agent Moving water creates runoff - water from rain or snow that flows into streams and rivers More runoff means more erosion! Moving water can form the following: 1.Streams 2.Valleys 3.Waterfalls 4.Deltas…. And more!

7 WATER EROSION Through erosion, a river can create valleys, waterfalls, flood plains, meanders, and oxbow lakes. 1. Waterfalls - formed when a river meets hard rock that erodes slowly 2. Flood Plain - flat, wide area of land along a river formed from water over gently sloping land

8 WATER EROSION 3. Meanders - a loop-like bend in a river that is formed from water flowing through soft rock 3. Oxbow Lakes - a meander that has been cut off from the river due to sediments from a flood

9 WATER DEPOSITION Every time water moves, it carries sediments with it that are dropped off in new places Through deposition, moving water can create landforms, such as deltas and alluvial fans 1. Deltas - a triangular deposit of sediment located at the mouth (end) of a river that empties into a still body of water (like an ocean or lake) 2. Alluvial Fan - a wide, sloping deposit of sediment formed where a stream leaves a mountain range

10 VIDEOS Summary of water erosion http://www.schooltube.com/video/e920ff2f44ed84d 96788/HowStuffWorks-Show-Episode-4-Power-Of- Water-Erosion What is the role of plate tectonics in water erosion? https://www.youtube.com/watch?v=f62_MjB6-Ok

11 GROUNDWATER EROSION Sometimes rain or snow melts and is soaked into the ground, filling in cracks in rocks, creating groundwater erosion Groundwater can cause erosion through chemical weathering. Water combines with carbon dioxide to create carbonic acid. Carbonic acid can wear down certain rocks and create caves.

12 AGENTS OF EROSION There are 5 agents (or causes) of erosion: 1.Gravity 2.Moving Water 3.Glaciers 4.Waves 5.Wind We are going to focus on the last 3 today!

13 (3) GLACIAL EROSION Definition : a glacier is a large mass of ice that move slowly over land 2 types of glaciers 1. Continental: glacier that covers most of a continent or large island and they flow in all directions 2. Valley : a long, narrow glacier that forms when snow and ice build up high in a mountain valley

14 ICE AGE An ice age is when a continental glacier covers a large part of the earth’s surface About 1 million years ago, 1/3 of earth’s land was covered in glaciers! What is the ice age? https://www.youtube.com/watch?v=dJ5GYQrkvxI Movie Preview: 1.What types of erosion do you see? 2.What about this preview is realistic? Unrealistic? https://www.youtube.com/watch?v=cMfeWyVBidk

15 HOW GLACIERS CAUSE EROSION 2 processes by which glaciers erode the land 1. Plucking: when rocks are broken by moving glaciers and then freeze to the bottom of the glacier. As the glacier moves, the frozen rocks stuck to the bottom move, too. 2. Abrasion : when these frozen rocks stay on the glacier and are dragged across the land. This dragging of rock can scratch the rock.

16 HOW GLACIERS CAUSE DEPOSITION Once a glacier melts, it deposits the sediment it eroded from the land, creating various landforms. These sediments deposited by a glacier are called till Glaciers can create the following landforms: Moraine - when a glacier deposits a mountain or ridge Kettle - a small depression or ice is left in a glacial till Fiord - a valley that was created by a glacier that is now filled with water Cirque - a bowl-shaped hollow eroded by a glacier

17 (4) WAVE EROSION How do waves cause erosion and deposition? Energy in waves come from the wind When the wind hits the water, waves form As the wave hits the shore, it moves the sand forward, then backwards into the water. The waves also shape the shoreline https://www.youtube.com/watch?v=775FQ5_YLvE

18 WAVE EROSION Waves shape the coast through erosion by breaking down rock and moving sand and other sediment Waves change direction based on the land masses that they hit A headland is a part of the shore that sticks out into the ocean

19 WHAT WAVES CAN CREATE Wave erosion can create… Sea Cave Wave-Cut Cliff Sea Arch Wave deposition can create… Beaches Sandbars Barrier Beaches Splits

20 (5) WIND EROSION Wind causes erosion by deflation. Deflation : the process by which wind removes surface materials, like sediments and sand, to new place Wind deposition occurs once the sediments picked up by wind fall to the ground. This can create… Sand dunes - wind blown sediments that has built up Loess deposits - pieces of sediment smaller than sand that are carried by the wind


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