Erosion

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Slide 1

The Work of Waves and Wind

Objectives:

Explain the characteristics of ocean waves and tides

Present coastline features of erosion, transport and deposition

Examine the processes of wind erosion and deposition

Differentiate different types of dune

Describe the wind deposit LOESS

Slide 2

Coastal landforms

wave length

wave height

crest

trough

particles in waves follow a circular pattern

Slide 3

At the shoreline

Water becomes shallow, wave height increases because wave length decreases

Waves become steeper, then collapse (breakers)

Slide 4

Surf - sequence of breaking waves

Swash - water sliding up beach

Backwash - water flowing back down beach to sea

Slide 5

Wave refraction

Close to coast, water gets more shallow

Waves are slowed down

If waves arrive at an angle, one part is slower than the rest

Causes waves to bend = wave refraction

Slide 6

Wave refraction

Bay

Slide 7

Waves arriving at bays are slow (deposition)

At headlands, faster (erosion)

Slide 8

A sequence of features is produced as headlands are degraded

Sea cliffs

Waves erode base -undercutting

the cliff retreats

Slide 9

Also produces sea caves

As cliffs retreat produces a wave-cut platform

Slide 10

Headlands may be eroded back leaving a remnant (stack)

stack

Slide 11

Longshore drift

Waves arrive at a coast at an angle (swash)

Backwash returns at 90 degrees

Sand is moved along the beach = longshore drift or longshore current

Slide 12

Coastal deposition

Result of longshore drift and a lot of sediment

= produces extensions of deposit from the shoreline

Slide 13

May grow across a bay (baymouth bar)