Review of CH 3 Sec 4-6: Glacier, Wave, Wind Erosion & Deposition

1. Review of CH 3 Sec 4-6: Glacier, Wave, Wind Erosion & Deposition Section 4: Glaciers Section 5: Waves Section 6: Wind Earth’s Changing Surface textbook

2. Three processes work together to wear down and shape the land: • Weathering- the process that breaks down rock on Earth’s surface. Why is weathering important? It creates sediment that becomes soil and/or part of a landform. 2. Erosion- the process of carrying sediment from place to place. Erosion is the major process that shapes the land. 3. Deposition- occurs when the agents of erosion lay down sediment. Deposition is important because it forms new land forms.

3. The 5 “Fabulous Agents of Erosion” • Gravity leads to mass movement of land • Moving water includes runoff and rivers • Glaciers  “moving ice” • Waves • Wind • Remember….the processes of weathering & erosion usually happen at the same time to break down and shape the land this is why sometimes its difficult to tell each process apart; just remember, weathering BREAKS rock into sediments, erosion MOVES the sediments • Deposition (LAYING down sediment) can also occur as erosion is moving sediment from place to place

4. Introduction to GLACIERS • http://www.brainpop.com/science/earthsystem/ • BrainPop only works on Google Chrome (teacher will play segment)

5. Sec. 4: Glaciers- “Rivers of ice”! • Glaciers are large masses of snow & ice that move slowly over the land • Continental glaciers are largest, cover most of a continent or an entire island, flow in all directions • Valley glaciers are long, narrow glaciers forming when ice/snow builds up in high mountains. They move down through valleys carved out by rivers • Glaciers form in areas where more snow falls than melts- this means large masses of snow & ice build up. • Average depth of glaciers is 30-40 meters, but can be thicker • Ice Ages are times in Earth’s history when continental glaciers covered large parts of Earth’s surface.

6. How do glaciers move? • Glaciers move under their own weight when gravity pulls them down a slope • Tremendous pressure at the bottom of the glacier causes the bottom layer of ice to melt (this is the part that moves) • Usually very slow moving…few centimeters at a time. But valley glaciers can move in a quick surge Two types of movement: • Glacial advance= when glaciers move forward down a slope  causes erosion of the land • Glacial retreat= glacier slows/stops moving, ice begins to melt  causes deposition of till it is carrying

7. How do glaciers shape the land? • Glaciers change the shape of the land as they move. Even though a glacier may not be seen, you can see evidence of glaciation on bedrock or in valleys. • Glaciers cause erosion by plucking and abrasion- weight of ice breaks rock, gravity causes glacier to move downhill, picks up sediment along the way, which freezes to bottom (plucking) • Sediment attached to the bottom of glacier scrapes the bedrock and also molds a V-shaped valley into U-shape. (abrasion)

8. How do glaciers shape the land? • Glacial till is made up of different sized sediments (sand to large boulders) that are carried or bulldozed by the moving ice, and left behind when the glacier retreats. • Till from deposition by glaciers form moraines = ridges of till (sediment) deposited by a retreating glacier. Long Island is an example of a terminal moraine- marks the ending location of the continental glacier from last ICE AGE

9. Plucking and Abrasion Click on the two links below: • landforms created by glacial erosion • http://www.wwnorton.com/college/geo/animations/glacial_advance_retreat.htm

10. Some features created or shaped by the action of glaciers!!! Glacial erratic- This HUGE boulder, called the Madison Boulder in New Hampshire, was carried and then dropped in the middle of the woods as the continental glacier that covered part of N. America advanced! Think of how powerful the glacier was to move this!

11. Some features created or shaped by the action of glaciers!!! Striations- Scratches and gouges in bedrock are evidence of abrasion by glaciers as they advance, eroding the land! Moraines- Ridges or mounds of glacial till (sediment) deposited when a glacier retreats (melts back)

12. Introduction to WAVES & WIND • http://www.brainpop.com/science/earthsystem/erosion/

13. Sec. 5: Waves • Like moving water in a river, waves also have energy • Waves get their energy from wind– wind blowing across the surface of the water transfers energy to water molecules which makes waves (KE) • Waves shape the coastal areas of the land See below for animation of wave energy: • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1604/es1604page01.cfm?chapter_no=visualization

14. How do waves shape the land? 1. BY ABRASION: • As waves approach the land, the water becomes shallower and the lower part of the wave drags along the bottom, creating friction. • The water picks up sediment (sand and gravel) and is carried forward by the wave’s energy • Abrasion by waves occurs when the sediment wears away rock on the land like sandpaper– over time, shaping a beach

15. How do waves shape the land? 2. BY IMPACT: • Impact is when the energy in large, powerful waves causes erosion to rock along the coast. • Large waves hit with great force, breaking apart rock  creates cliffs, headlands, sea caves, and sea arches (these landforms are created when erosion occurs) • The softer rock wears away first; harder rock resists erosion longer • Link for wave erosion: http://www.wwnorton.com/college/geo/animations/cliff_retreat.htm • On this site, click on each NUMBER and turn on the TEXT to read what is happening: https://hwb.wales.gov.uk/cms/hwbcontent/Shared%20Documents/VTC/2009-10/geog/mj-coasts/eng/1/animation_definition.swf

16. Landforms created by wave deposition • When waves carrying sediment slow down as they approach a shallow area, sediment can be deposited • Wave deposition can form beaches along the coast, sandbars (underwater most of time), and barrier beaches (above water, parallel to the coast) • click on longshore drift to see a beach forming

17. Sec. 6: Wind • Acting alone, wind is the weakest agent of erosion • Wind causes very little erosion to the land, but does carry and deposit sediment long distances. • Wind causes erosion by picking up loose sediment and carrying it away, leaving behind the larger rocks • Wind-carried sand can be deposited in large sand dunes (found on beaches or in deserts) • Abrasion by wind carried sediment can polish rock, smoothing it out. • sand dune formation- click on 2nd animation

18. Fun W.E.D. Review Websites • Fossil Fun - http://www.abc.net.au/beasts/fossilfun/ • 2. Video (3 min) - https://www.youtube.com/watch?v=lyysL02ZvQ8&noredirect=1 • Shape it Up activity - http://sciencenetlinks.com/interactives/shapeitup.html • http://www.kineticcity.com/mindgames/warper/ • 4. Review Game with soccer, basketball, or Deal/No Deal – • http://sciencereviewgames.com/srg/subjects/games.php?id=18 • or http://sciencereviewgames.com/srg/subjects/games.php?id=19 • 5. Choose a review game - http://reviewgamezone.com/game.php?id=32