Wind and Wave Erosion. How is wind abrasive? It carries sand grains that grind and scour anything...
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Transcript of Wind and Wave Erosion. How is wind abrasive? It carries sand grains that grind and scour anything...
Wind and Wave Erosion
How is wind abrasive?
• It carries sand grains that grind and scour anything that they hit.
What is Loess and how does it form?• It can be 1m to 100m deep. • Made of mineral & rock
particles. • It is wind-carried sediment &
when dropped, it will hold together so well that when it erodes, it splits off vertically to form cliff-like slopes.
• Main deposits of loess in the U.S. include Mississippi & Missouri river valleys.
What is a sand dune?
• Sand dunes - hills of sand deposited by wind. They form when the sand piles up against shrubs, boulders, or other substances.
How does a Sand Dune Migrate?
• When wind blows against the windward side (side facing into the wind) of a dune, some of the surface sand is carried over top & falls on the leeward side (side facing against the wind)
Types of Sand dunes• 1. Barchans – crescent-shaped & the ends of a
barchan point downwind.
Types of Sand dunes• 2. Transverse – Where sand is more abundant,
long continuous sand ridges form at right angles to the wind.
• Found on beaches.
Types of Sand dunes• 3. Parabolic – (u-shaped) dunes often form
around blowouts. Unlike barchans, the open ends of parabolic dunes face upwind.
• Found on beaches.
Types of Sand dunes• 4. Longitudinal – Form in desert regions with
lots of sand. These dunes are long, straight ridges that are parallel to the general wind direction.
Draw a wave and label its parts (Crest, Trough, Height)
How do swash and backwash work together?
• Swash - the motion of water up the beach.• Backwash – the motion of water running back
down the beach
What is a longshore current? How does it affect someone swimming at the beach?• It runs parallel to shore. It moves people
down the beach.
What is a rip current? Why is it dangerous?
• Strong surface currents that flow away from the beach. They can reach up to 5 km/hr. & carry you away from shore.
Describe the process of a sea cliff turning into a sea stack. (4 parts)
• 1. Sea cliff - waves cut out rock & make a notch
• 2. Sea cave - notch will deepen & make a hole
• 3. Sea arch – waves cut through walls of sea caves to make an arch
• 4. Sea stacks – roof of sea arch falls into water
What is a sandbar?
• A sandbar is a bar of sand formed by ocean currents depositing sand near the shore underwater
What is a spit?
• A sandbar attached at one end to the shoreline.
What is a hook?
• A spit with a curved end
What is a barrier island?
• Barrier islands are sandbars not attached to land or the shoreline and are above water
What is a tombolo?
• A tombolo is a bar of sand that joins an island to the mainland.
What is a bay mouth bar?• A bay mouth bar is a spit that completely
closes access to a bay, thus sealing it off from the main body of water.