Erosional forces

Daily Dose of Destruction

Mass Movement Internet Search

Daily Dose of Destruction

Erosion

• Erosion wears away surface materials and moves them from one place to another.
• Agents of erosion are gravity, glaciers, wind, and water.
• Only erodes when they have enough energy.
• Agents drop the load when energy decreases.
• dropping heavier sediment first.
• Deposition is the process of erosion droppings its load.

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Mass Movement Type: Slump

• Soil and rock slip downslope in one large mass.
• Water penetrates the upper layer but doesn’t flow through lower layers.
• Leave curved scars.
• Most often after earthquakes, heavy rains and prolonged rains.
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Mass Movement Type: Creep

• Creep, sediments slowly make their way downhill.
• Evidence: Tilted power poles and fence lines.

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Mass Movement Type: slides

• Falling rocks.
• Occur in mountainous areas or where there are steep cliffs?
• Evidence: Talus slopes

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Rockslide

Mass Movement Type: Mudflow

• Wall of mud
• Thick, moves like a thick liquid.
• Usually occur in relatively dry areas where weathered material accumulates.
• Caused by prolonged rains and saturation.
• Spreads out into a cone shape called and alluvial fan.

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Mudflow

Lahar

• Mudflow caused by volcano
• Ice melts quickly

Lahar

Oso Landslide

2014

10:30 AM

43 Deaths

Oso Washington

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What is the angle of repose?

Info: Angle of repose = The steepest angle at which a sloping surface formed of a particular loose material is stable. Once the material has hit the angle of repose, a mass movement event is inevitable if the angle gets any steeper.

Angle of Repose Lab

Daily Dose of Destruction

Erosion and Deposition by Glaciers

• Glacier is a large mass of moving ice and snow.
• Formation of glaciers
• When snow doesn’t melt it piles up.
• The heavy snow layers on top compress the layers below that there is enough friction to slightly melt the lower layers.
• Becomes sort of like putty on the bottom
• It slowly starts to move due to gravity downhill.

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Two types of Glaciers: Continental

• Continental glaciers: huge masses of ice and snow that cover large areas of land.
• Have been guessed to have covered 28 percent of the Earth.
• Ice ages
• Last ice age was about 2-3 million years ago.
• Glaciers today cover about 10 percent of the Earth
• They can be so large that they weigh enough to push some crust into the mantle.
• Large enough to cover mountains and carve out great valleys.

Two types of Glaciers: Alpine or Valley

• Alpine glaciers: Smaller glaciers that continue to carve out mountains and valleys
• Still have a few.

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Himalayan Glaciers

Phet Glacier Lab

Log into your Google Docs

Go to the following link.

http://tinyurl.com/PhetGlacier

One of you in your group will create a copy. You will then share a copy to your group members.

You may divide and conquer the questions, but do the simulation together.

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Daily Dose of Destruction

Evidence of Glacial Erosion: Aretes

Evidence of Glacial Erosion: U-Shaped Valleys

Evidence of Glacial Erosion: Cirque

Evidence of Glacial Erosion: Horn

Evidence of Glacial Erosion: Hanging Valley

Evidence of Glacial Erosion: Plucking and Grooves

Glacial Deposits

• Till: Mixture of different sized glacially deposited sediments
• Drumlin: Hills made of reshaped glacial till.
• Erratics: Large rocks deposited in the middle of nowhere.
• Moraines: Deposits that make a ridge
• Outwash plains: Material deposited by meltwater.

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Glacial Deposits: till

Glacial Deposits: Drumlins

Glacial Deposits: Erratics

Glacial Deposits: Moraines

Glacial Deposits: Outwash Plains

Watch Chasing Ice

Daily Dose of Destruction

Erosion: Wind

• Deflation: wind blowing across loose sediment, removing small particles like clay, silt, and sand, leaving course materials like gravel behind.
• Abrasion: windblown sediments strike and chip off pieces of larger rocks.

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Erosion: Wind

• Haboob: sand storm
• Wind can carry lighter clay and silt many miles away in the atmosphere.
• Wind is plays a huge part in soil erosion.

Wind Erosion: Reducing techniques

• Windbreaks
• Plant roots

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Wind Erosion Deposition

• Loess: Large deposits of windblown sediments.
• very fine grained, in fact as fine as talc.
• Many fertile fields are because of loess.

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Other types of wind erosion features

Desert Varnish

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Ancient Dunes

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Wind Erosion Deposition: Dunes

• Sand dunes start by sediment piling up on one side of wind blockage, shrub, rock, etc...
• Dunes can get very high because the higher they grow the more sediment can become trapped by them.

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Sand Dune Migration

• Sand dunes constantly shift and move
• called dune migration
• Side facing the wind has gentle slope.
• Dunes move away from the direction of the wind.

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Formation of the Great Sand Dunes National Park

Types of sand dunes

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Sand Dunes Lab

Kahoot Review/Test