Download 5-3 Notes: Waves and Wind Erosion Think About Waves and

5-3 Notes: Waves and Wind Erosion
Think About
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How do you think these pillars of rock formed?
Waves and Currents
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The rock pillars were formed by the constant action of
_______________________ slowly wearing the rock away.
In the future, waves will most likely wear away the pillars
___________________________________.
Waves are powered by _______________________ and can wear away rock and move thousands of tons of sand.
Shorelines
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High, rocky coasts tend to get worn _____________________ by waves, while ______________ coastlines are
often BUILT UP.
When a stream flows into an ocean or lake, it deposits ________________________________ near its mouth.
This sediment mixes with the sediment formed by waves crashing against the shore.
Waves and currents move this sediment along the shore, building up _________________________________.
Longshore _________________________: the zigzag movement of sand along a beach.
Waves hit the beach at an angle due to the direction ____________________ is blowing.
Gravity then pulls the sand straight back down to the water
This process eventually shifts the sand down the beach in a __________________________________ pattern.
Longshore _______________________: movement of water along a shore as waves strike the shore at an angle.
The direction of the longshore current can change as the direction of the waves striking the shore
______________________.
Sandbars and Barrier Islands
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Longshore currents often deposit ______________ along shorelines.
Sometimes the sand can build up to form a sandbar-a completely or
partially submerged ridge of sand.
Spit- A sandbar that has built up above the water’s surface and is
joined to land at one end
Barrier Island- over time, sandbars can build up into long narrow islands
that develop parallel to a coast (start out as sandbars)
Barrier islands get their name from the fact that they create a barrier between ocean waves and the shore of the
______________________________.
Wind Shapes Land
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Wind has the power to transport and deposit sediment.
Wind is less powerful than water but it still shapes landforms, especially in dry regions or regions with few plants.
Wind can:
o Build up dunes
o Deposit layers of ___________________
p. 85
o Make a land surface as hard as pavement
Dune Formation
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Dune- a mound of sand built up by wind.
Even a ____________________________ breeze can carry dust.
A moderate wind can roll and slide grains of sand along a beach.
Only a very strong wind can pick up and carry ____________________ particles.
When the wind dies down or hits something (e.g. a cliff or hill) it drops the sand.
Over time, the sand builds up to create __________________________.
Some dunes start out as ripples that grow larger.
Others form as wind-carried sand settles around a rock, log, or other ____________________________.
Dunes vary greatly in size and shape and can reach heights of ___________ m!
Some dunes are curved; others are straight.
There is usually a gentle slope on the side facing the wind and a steep slope on the side facing
________________________ from the wind.
Loess
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Wind also changes the soil over large regions of Earth by depositing _______________________.
A strong windstorm can move millions of tons of dust.
____________________________: deposits of very fine wind-blown sediment. (pronounced LOH-uhs)
In some regions, deposits of loess have built up over thousands or even millions of years.
Loess is a valuable _____________________________________ because it forms good soil for growing
crops.
Loess covers about 10% of Earth’s land surface.
Desert Pavement
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Wind can shape land surfaces by _____________________________ dust.
When wind blows away all the smallest particles from the soil, it leaves behind a hard layer of stone and
________________________.
This is called desert pavement because it looks like cobblestone.
Review
____1. In which of the following areas is wind a major erosion agent?
A. a grassy field
C. sand dunes in the desert
B. an area covered with pine trees
D. a hillside covered with plant life
____2. A dune is a sand mound built up primarily by
A. gravity
B. running water
C. glaciers
D. wind
____3. Strong winds can transport large quantities of
A. gravel
B. wet sand
C. dry sand
D. clay