Agents of Erosion

Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil.

Water Erosion Rivers, streams, and runoff

Ice Erosion Glaciers

Wind Erosion

Mass Movements Landslides, mudslides, slump and creep landslide clip.mpeg

Shoreline Erosion Erosion- the removal and transport of material by wind, water or ice Weathering- the breakdown of rock into smaller and smaller pieces by mechanical or chemical means Deposition- materials are dropped

Shoreline Shoreline- where land and a body of water meet. Deposition- materials are dropped Waves are powerful agents of erosion and deposition

Waves Wind moves over the ocean= waves The size of the wave depends on the size of the wind Waves may travel many kilometers Waves don’t travel alone They travel in groups called wave trains Breaking waves are known as surf The wave period is the time interval between breaking waves

Pounding Surf Energy is released when waves break A wave can break rock or throw broken rock Waves wash into cracks of rock and break off boulders (huge rocks) or sand. New beaches can form!

Wave Deposits Waves can carry materials, including sand, rock fragments, and shells. Beach- any area of the shoreline made up of material deposited by waves Not all beaches are the same

Beaches are made of different types of material deposited by waves. Compare the beaches… Beaches are made of different types of material deposited by waves.

Stormy seas= pebbles and larger rocks Compare the beaches… Hawaii- eroded lava Pieces of seashell Stormy seas= pebbles and larger rocks

Wave Angles The way sand moves depends on the angle of the waves on the shore Waves come to shore at an angle Waves normally leave in an angle perpendicular to the shore Longshore current- water near and parallel to the shoreline

Wave Angles Sand Movement Longshore Current Wave Direction

Wave Angles- Diagram

Offshore Deposits Waves erode material from the shoreline and transports and deposits it Landforms are created in open water

Wave Erosion Waves strike (hit) and erode rock and wear away soil and rock How quickly sea cliffs erode depends on the hardness of the rock and the energy of waves

Wave Erosion

Wind Erosion Has wind ever blown your papers? You already know how wind erosion works!

Take cover! Loose rock material Deserts Coastlines Plants Plant roots anchor (keep down) sand and soil

Wind Erosion Wind moves material in different ways Material is moved by saltation Saltation is the movement of sand-sized particles by skipping and bouncing in the direction of the wind

Particles roll forward or bounce in the air. Saltation Particles roll forward or bounce in the air.

Deflation is the lifting and removal of sediment by wind

Deflation

Deflation

Deflation Before After

Deflation hollows

Abrasion Abrasion is the grinding and wearing down of rock surfaces by other rock or sand Strong winds Loose sand Soft rocks

Wind Deposited Material All material carried by the wind is eventually deposited Dunes (common in deserts and along shores) Loess

Loess is finer than sand. It feels like powder.

Glacier Glacier- mass of moving ice 2 types Alpine Continental Glacier

Glacier Form in areas of snow on ground all year High elevations Polar regions

Glacier Snow piles up snow packs crystals Giant ice mass “Rivers of Ice”- begin to move (gravity)

Alpine Glaciers Forms in mountainous areas Valley Glacier- form in valleys with streams flowing downhill Forms a U- shape

Continental Glacier Not all glaciers are “rivers of ice” Can spread across entire continents Continental glaciers- continuous masses of ice

Continental Glacier Continental ice sheet- largest type of glacier* Antarctica is almost completely covered by an ice sheet Contains 91% of glacial ice on planet ½ times the size of United States It is 4,000 m thick in some places; covers everything except highest mountain peaks

Ice Shelves Ice shelf- an area where ice is attached to the ice sheet but resting on open water Ross Ice Shelf- largest ice shelf Attached to ice sheet covering Antarctica

Ross Shelf

Ross Shelf

Icebergs Large pieces of ice that break off an ice shelf

Icebergs form by calving Large pieces of ice that break off an ice shelf Icebergs form by calving

The Titanic Most of an iceberg is below the surface Hazard for ships