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AIM: How do Glaciers change the landscape? Do Now: As a bulldozer moves over the land, describe what happens to the ground as the shovel moves across it.

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Presentation on theme: "AIM: How do Glaciers change the landscape? Do Now: As a bulldozer moves over the land, describe what happens to the ground as the shovel moves across it."— Presentation transcript:

1 AIM: How do Glaciers change the landscape? Do Now: As a bulldozer moves over the land, describe what happens to the ground as the shovel moves across it. Then describe what the pile of sediment looks like after the bulldozer moves away Perito Moreno Glacier, Argentina

2 Thick masses of ice that form over hundreds or thousands of years. I. Types of Glaciers Valley Glacier: a stream of ice that flows between steep rock walls (valleys). Ice Sheets: also called continental ice they flow in all directions covering the land.

3 II. Glacial Movement - Glacial movement is called Glaciers advance when they accumulate (gain) more ice from freezing at the glaciers head. They also slide very slowly down hill due to gravity. Glaciers retreat when they lose more ice from pieces falling off or melting.

4 III. Glacial Features A. Erosion - Glaciers cut “U- shaped” valleys through the ground. These form in glacial valleys - Erosion also creates Cirques, Arêtes and Horns.

5 Plucking and Abrasion - Plucking- when glaciers loosen and lift up rocks from the surface. - Abrasion- rocks trapped in the glacier grind against rocks on the surface as the glacier moves. This creates scratches and grooves in the bedrock, called striations.

6 B. Deposition -Glaciers create till, which is unsorted sediment deposited by the glacier. -Deposition also creates kettles, outwash plains and moraines, which are ridges of unsorted of till. -Glacial Erratic are large boulders left behind from melting glaciers

7 IV. Glaciers and Long Island The red on Long Island and Connecticut indicates two moraines formed by two different glaciers. The first ended about 21,000 years ago and formed the Ronkonkoma moraine (South Shore). The second, ended about 10,000 years ago and formed the Harbor Hill moraine (North Shore).

8 Closure Obtain a worksheet on Glaciers. With the person sitting next to you use the notes to answer the questions on the handout. You have about 5 min to work on it

9 How do Glaciers Change the Landscape? - Worksheet Ice SheetsGlacial Valley Thinner, flat expanse of ice Covers continents and can extend out into oceans Also called continental ice Creates “U- Shaped” trough Moves between two mountains (steep rock) Occurs only on continent 1.

10 2. Plucking is when glaciers loosen and pick up rock off the surface of the Earth. Abrasion occurs when rocks trapped in the glacier grind against rocks on the surface of the Earth. 3. It was created by a glacier because of the “U-shaped” valley that was created

11 4. Over the last 25,000 years glaciers have shaped the land in New York. Glaciers advance when they freeze more water than melts away. At two different times glacial advances plucked sediment out of the ground and moved it South. During glacial retreats, when more water melts than freezes, the sediment was left behind to form two moraines. These moraines later became the North and South shores of Long Island.

12 AIM: How does Wind change the Landscape? Do Now: In your notes, describe how a sand blaster works. If your not sure, ask the person sitting next you. Then describe how nature could create “ a sand blaster”. What would you need? Namib Desert of Namibia, Angola

13 I. Wind Erosion Wind erosion is most effective in deserts. Strong wind erodes great quantities of fine sediment leaving coarse sediment behind. A.Deflation: occurs when wind lifts and removes loose particles like silt and clay. Larger particle skip and roll along the surface. B. Abrasion: occurs when wind blown particles cuts and polishes exposed rock acting like a sand blaster. Double Arch, Arches National Park Utah

14 II. Wind Deposition - Wind creates deposits of sediments that are sorted (graded).  As energy is lost, larger particles are dropped first. Smaller particles are on top Larger particles are on the bottom

15 A. Loess: windblown silt that blankets the landscape.

16 B. Sand Dunes: are mounds or ridges of sand that are created when wind blown sand encounters and obstruction. - Sand dunes have a gentle slope on the side the wind is blowing from, windward side. The side that is sheltered from the wind is at a steeper slope, sheltered side. WIND

17  Crossbed – sloping layers caused by sand being deposited on the sheltered side of a dune. Lithification turns this sediment into sedimentary rock and the crossbeds are still seen.

18 Closure Obtain a worksheet on Wind. With the person sitting next to you use the notes to answer the questions on the handout. You have about 5 min to work on it

19 WIND 1. Wind pushes sediments up gently along the slope facing the wind. Sediment falls off the other side creating a steeper slope. 2. Deflation lowers the land removing necessary soils for farmers to grow their crops in. 3. There is nothing to block the wind and there is an endless supply of sediments to move around.

20 4. How should the sediment look after it was transported by the wind?

21 AIM: How do waves shape the Shoreline? Do Now: In your notes answer the following questions. Think about the times you were at the beach. Maybe you built a sand castle near the shore line. What would the waves do to your castle? Describe in detail he sequence of events that occur after you built your castle and the waves come in.

22 I. Forces acting on the Shoreline - Waves constantly erode, transport and deposit sediment along the shoreline. - Storms increase the activity of waves.

23 A.Longshore Drift : occurs when currents flow parallel to the beach and carry large amounts of sediment. - This current easily moves fine sediment and rolls larger sediment along the bottom.

24 II. Wave Erosion - Waves constantly remove sediment from the shore line. -Wave action causes abrasion to occur forming Sea Arches and Sea Stacks

25 III. Wave Deposition - The accumulation of sediment along the shore is called the beach. A.Sand bars: constantly shifting mounds of sand that form from the deposition of material from long shore currents. A.Barrier Beaches (Islands): Permanent larger sand bars that form parallel and separate from the coast. Create bays.

26 IV. Beach Preservation - Groins, Jetties, sea walls and breakwaters all protect a coast from erosion or prevent the movement of sand along the beach. - The side of the groin with deposited sand indicates the direction of erosion along the shore. Wave path

27 Where are the waves coming from?

28 Closure: Obtain a worksheet on Waves. With the person sitting next to you use the notes to answer the questions on the handout.

29 1. Where is the longshore wave coming from? 2. Jetties keep sand from being eroded away from the beach. They catch the sand and force the wave to deposit it nea2 the jetties.

30 3. Wave erosion creates sea arches and sea mounts because of differential weathering by the waves. Wave deposition creates sand bars and barrier islands due to deposition of the sand.

31 ProcessDifferencesSimilarities Glacier Wind Wave


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