Name: _________________________________ Date: _______________ Period: _____ Due Date_______
Erosion and Deposition Discovery Stations
Waves
The energy in waves comes from wind that blows across the water’s surface. Waves are the major force of
erosion along the coasts. Waves can erode land by impact and abrasion. Eventually, waves may erode the base
of a cliff that the rock above collapses. The result is a wave-cut cliff. Another feature created by wave erosion
is a sea arch. A sea arch forms when waves erode a softer rock that underlies a layer of harder rock. Waves not
only erode the land, they also deposit sediment. As waves reach the shore, they drop the sediment they carry,
forming a beach. A beach is an area of wave-washed sediment along a coast. The sediment deposited on
beaches is usually sand. Some beaches however are made of small fragments of coral or sea shells piled up by
wave action.
1. What are two of the processes by which waves can cause erosion? _________________________________
2. How is sediment deposited along the coast? ___________________________________________________
Waves usually hit shores diagonally because
a shoreline’s shape varies.
3. What happens to the water that travels onto the beach with the wave? _______________________________
4. What force causes this “backwash”? _________________________________________________________
5. Waves often push water up onto a beach an angle, but gravity pulls it back perpendicular to the shore. Draw
an arrow that shows this perpendicular movement of water.
6. Draw several more arrows zigzagging up or down the beach. How does this affect particles of sediment on
the beach? _______________________________________________________________________________
Inquiry Challenge-Do large waves erode more than small waves?
Materials-aluminum baking pan, sand, water, metric ruler, piece of cardboard
1. Build a small sand hill on one side of the pan.
2. Add water and make waves with the small piece of cardboard.
3. Make small waves and then large waves.
What relationship did you observe about wave size and erosion?
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Wind
Wind is the weakest agent of erosion but is very powerful at shaping the land in areas where there are few
plants to hold the soil in place. The main way that wind causes erosion is by deflation. Deflation is the process
by which wind removes surface materials. The stronger the wind, the larger the particles it picks up. Abrasion
by wind carried sand can polish rock but causes little erosion. All of the sediment picked up by wind eventually
falls to the ground. Wind erosion and deposition may cause sand dunes and loess deposits. When the wind
strikes an object, the result is usually a sand dune. Sand dunes are typically made up of coarser sediments
carried by wind. The finer sediments are sometimes deposited in layers far from their source. This is called
loess. Large loess deposits help form fertile soil.
1. What are two ways wind can cause erosion? ___________________________________________________
2. How do sand dunes and loess deposits form? __________________________________________________
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As wind speed increases over soil with no vegetation, small sand particles (0.1–0.5 mm in diameter) begin to
move. At first, particles on the surface creep forward. As wind speed continues to increase, small particles fly
through the air for a few centimeters before falling back to the surface. This is called saltation. When the
saltating particles hit the ground, they may dislodge other particles, especially smaller particles. Finally, if the
wind speed is high enough, small particles become suspended in the air. Suspended particles are carried high
into the air where they become the dust of a dust storm.
3. Which of the three ways shown in Figure A would likely have carried the sediment to this loess deposit seen
in Figure B? _______________________________________________
http://images.travelpod.com/users/lroff/world_2006-2007.1146957120.06-loess-bluff.jpg
Inquiry Challenge-How Does Moving Air Affect Sediment?
Materials-pan, cornmeal or sand, straw
1. Cover the bottom of a pan with a flayer layer of cornmeal or sand (1-2 centimeters deep)
2. Gently blow over the layer of sediment using a straw to direct your breath. Observe what happens.
What changes did the wind you created make in the flat layer of sediment?
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Glaciers
Glaciers can form only in an area where more snow falls than melts. The movement of a glacier changes the
land beneath it. They move slowly but are a major force of erosion. Plucking and abrasion are the two
processes by which glaciers erode the land. Plucking is when a glacier flows over the land and picks up rocks.
The rock fragments can freeze to the bottom and is carried along with the glacier, it was “plucked” from the
ground. Abrasion is when rocks remain on the bottom of a glacier and are dragged across the land. Along the
way it scratches the bedrock below. As it travels glaciers collect a large amount of rock and soil. When a
glacier melts it will deposit this sediment creating different landforms. A till is the mixture of sediments that a
glacier deposits on the surface. The till on the edges of a glacier form a ridge called a moraine.
1. What are two types of glacial erosion? _______________________________________________________
2. Describe three features formed by glacial deposition. ____________________________________________
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Inquiry Challenge-Glacial Deposition
Materials-ice cube, modeling clay, sand, cardboard
1. There is a modeled landscape made out of clay with sand at your station, sprinkle with extra sand if needed.
2. Slide an ice cube over the clay and sand.
3. Leave the ice cube to melt at the end of the path.
4. Sketch and write a description of the model glacial landforms you have made. Use the graphic above to
assist you.
Water Erosion
Moving water is the major agent of the erosion that has shaped Earth’s land surface. However, water in all its
forms can cause erosion. Raindrops (especially in dry environments) create splash erosion that moves tiny
particles of soil. In streams, water is a very powerful erosional agent. The faster water moves in streams the
larger objects it can pick up and transport. Fine sand can be moved by streams flowing as slowly as threequarters of a mile per hour. Streams erode their banks in three different ways: 1) the hydraulic action of the
water itself moves the sediments, 2) water acts to corrode sediments by removing ions and dissolving them and
3) particles in the water strike bedrock and erode it. Through erosion, a river creates valleys, waterfalls, flood
plains, meanders, and oxbow lakes. As water moves, it carries sediments with it. Any time moving water slows
down it drops or deposits some of its sediment. Deposition creates landforms such as alluvial fans and deltas.
It can also add soil to a river’s flood plain.
Groundwater is when some rain and snow soaks into the ground. Groundwater can cause erosion through a
process of chemical weathering. When water sinks into the ground it combines with carbon dioxide to form a
weak acid called carbonic acid. This can break down limestone hallowing out pockets in the rock. Over time
these pockets become very large forming caves and caverns. Deposits called stalactites and stalagmites often
form.
1. What is the major cause of erosion on Earth’s surface? _____________________________________
2. What are the results of deposition along the course of a stream or river? _____________________________
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3. How can groundwater contribute to erosion? __________________________________________________
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4. Using Figure 1 below answer the following questions.
a) What happens to the Mississippi River as it flows
through its delta? _________________________
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b) Can you find the river’s main channel? Label on Figure
1.
Inquiry Challenge-Raindrop Erosion
Find out how the force of falling raindrops affects soil
Materials-Petri dish, soil, water, pipette, meter stick
1. Fill a Petri dish with fine textured soil to a depth of about 1 cm. Make sure the soil is flat but not packet in.
2. Place the dish on paper.
3. Fill a dropper with water. Squeeze a large water drop from a height of 1m onto the surface of the soil.
Repeat 4 times.
4. Use a meter stick to measure the distance the soil splashed from the dish.
5. Repeat steps 1 through 4, this time from a height of 2 m. Which traveled further, the splash from 1 m or the
splash from 2 m?
6. Which test produced the greater amount of erosion? Why?
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