Beach Erosion and Deposition
• Compare the effects of wave
frequency on beach erosion and
on deposition.
• Describe how shoreline slope
affects the rate of beach erosion.
• Determine how beach
composition affects erosion.
If you visit a beach often, you will become familiar with the many features
that make a beach unique. For example, you will begin to notice how the
beach slope changes as you approach and enter the water. However, if you
return to the beach after a major storm, you will see how quickly the beach
can change as wind and waves remove or deposit large amounts of sand
and other material. In this activity, you will explore how waves influence
the development of shorelines through erosion and deposition.
Procedure
1 Use Mixture A to construct a model beach at one end of the plastic
• 200 mL Mixture A (75% sand,
25% gravel)
• 200 mL Mixture B (25% sand,
75% gravel)
• clear rectangular container
container. The model beach should extend across the entire end of the
container and slope gradually toward the opposite end. The beach
should be 3 cm deep at its highest point and extend 5 cm into the
container, as shown in the diagram below. (You may not need to use
the entire 200 mL of mixture.)
• masking tape
• thin permanent marker
• metric ruler
3 cm
• 100-mL beaker
• water
• small wooden block
(5 cm 10 cm)
• stopwatch
2 cm
5 cm
2 Tape a strip of masking tape to a vertical edge of the container
opposite the model beach. Use the marker to mark the tape 2 cm from
the bottom. Use the beaker to fill the container with water to the 2-cm
mark. Add the water slowly at the opposite end of the beach so you
do not disturb the setup.
3 Place the wooden block in the water at the end
Model
beach
Plastic
box
Wood
block
of the container opposite the shoreline. Place the
long side of the block parallel to the shoreline
(see diagram to the left). Without removing the
block from the water, generate waves by moving
the block up and down for two minutes at a rate
of one wave per second. Make sure the rate and
size of the waves remain constant.
Water
4 After two minutes, sketch a cross-section of the
slope of the model. In your sketch, record the
former slope and position of the model beach
and show the new distribution of the sand and
the gravel.
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Unit 4 Earth’s Changing Surface