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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WindWind 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? ____________________________________________________________________________________________________________________________________________

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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GlaciersGlaciers 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. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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 ErosionMoving 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 three-quarters 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? _________________________________________________________________________________________________________________________________________________________________________________________________________________3. How can groundwater contribute to erosion? ____________________________________________________________________________________________________________________________________________4. Using Figure 1 below answer the following questions.

a) What happens to the Mississippi River as it flows through its delta? _________________________ _______________________________________

b) Can you find the river’s main channel? Label on Figure 1.

Inquiry Challenge-Raindrop ErosionFind 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? ____________________________________________________________________________________________________________________________________________________________________________________