What surface features are caused by constructive processes? What do you think of when you hear the word constructive? Deposition (deltas, sand dunes, etc.) is a process in which layers of a substance form gradually over a period of time. Earthquakes are sudden movements of Earth’s crust. This happens where there is a fault line. Faults are weaknesses in the rock strata that can shift and create an earthquake.

They are usually followed by aftershocks. Volcanoes occur because of the heat and liquid built up. A volcano will finally rupture and release molten lava, hot ash, and

What kinds of surface features are caused by destructive processes? What do you think of when you hear the word destructive? Weathering is the gradual breakdown of rock with changes of certain surface conditions. It can be a physical change, like a change in color, or it can break down completely. Weathering creates residue that can be washed away. Erosion is a gradual breakdown of something, and it happens naturally. An example is a sand dune. On a very windy day, the sand dunes change shape because the sand is carried away to another location. Erosion means weathering plus transportation at the same time. Impact of organisms can also cause destruction. Believe it or not, people and animals are constantly eroding Earth around

Example of deposition: sand dune

Volcano

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them. It can be as simple as dirt being washed out of a flower bed or it can be as massive as construction crews blasting tunnels through mountains. How can earthquakes and volcanoes be both constructive and destructive processes? Destructive forces break down Earth. Many things can happen, like the eruption of volcanoes, the massive shaking of earthquakes, or simply the constant flow of a river.

gases into the air. Did you know that there are many different types of volcanoes? Do you know what makes them different?

What is the role of technology in controlling constructive and destructive processes? How do humans intervene in the control of constructive and destructive processes? Some ways include seismological studies, flood control, and beach reconstruction. Why is human intervention important? How does it help control constructive and destructive processes?

Seismology is the study of earthquakes. Scientists use a seismograph to measure the movement of the ground during an earthquake. They then use that information to determine the severity of an earthquake. The Richter scale measures the earthquakes on a scale from 1 to 10 depending on how much Earth moves, causing the earthquake. However, scientists have begun to use a newer scale to measure earthquakes. It is called the Moment Magnitude Scale (MMS).

Destruction from earthquakes

Why are dams, levees, and storm drains important? All of these things must be taken into consideration when building new communities. These are all ways to control flooding.

Example of a dam

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Weathering and Erosion

Weathering causes rocks to split into smaller pieces. There are three main types of weathering: physical, chemical, and biological. Physical weathering changes the size, color, and shape of a rock. It will not change its chemical makeup. Physical changes can be caused by rocks tumbling or by the freeze and thaw cycle of water. Chemical weathering is caused by a chemical reaction between rocks and water. It can also be caused by gases in the air. Water, especially acid rain, can dissolve certain minerals like calcite, limestone, or marble. Oxygen in the air will react with iron or manganese by forming iron oxides. This process is commonly known as “rusting.” Biological weathering can be caused by plant roots growing into rock. Also, lichen and certain animals will excrete chemicals that cause this process. As rock is weathered, it breaks up into smaller and smaller pieces. Those pieces become sand.

What are things that can be done to save erosion of beaches? What is beach reclamation? How is it done?

Beach reclamation is the process of reclaiming a beach from erosion. Beach reclamation is done by dredging beaches. Dredging is when sand is scooped out of deeper water and drawn out to “reclaim” the area where erosion occurred. This helps rebuild the shoreline that once was there. Reclamation does not just occur on ocean beaches but any beach or shoreline that is subject to severe erosion. This process is also used in lakes and rivers to get sand. The sand is then brought to the areas that need to be reclaimed.

Once the sand is obtained, it is deposited at the site. The sand restores the shoreline to its original borders or extends the beach farther into the body of water.

Where does sand come from? How can studying sand samples tell you where it came from? Why is most sand white or beige?

Can beaches be made up of something other than sand? Does a particle have to be a certain size to be considered sand?

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Gather these materials to make conclusions on where the mystery sand is found:

A variety of sand samplesA variety of soil samplesMagnifying glasses or microscopes Black and white paper

Look at the different samples of sand. By looking closely at them, can you determine the type of rocks they are made of? What does the sand tell you about where it may have come from? How do the soil samples vary from the sand samples? Are they composed of different materials?

After investigating the sand, do some research to answer the questions above.

Facts About Volcanoes

• Pressure builds in a volcano until it cannot contain the pressure anymore. The liquid and heat build up and force the lighter, melted rock buried deep below the surface toward the surface of Earth, causing an eruption.

• The high and low pressures cause enough of a disturbance that the magma rises to the surface and spills over the top.

• The eruption of magma on the surface of Earth can take up to several hundred years to cool, depending on what it is made of and where on Earth it has occurred.

• The molten lava that flows down the side of a volcano is composed of a mixture of gases, liquid rock, silica, and crystals.

Effects Animals Have on Erosion

Animals are one of the biggest causes of erosion. There are billions of animals that dig up the soil in search of food and homes. Think about moles, prairie dogs, and beavers and the amount of damage they cause building their homes. Insects, worms, reptiles, and mammals also cause damage. They disturb the upper layers of soil, which causes the wind and rain to wash it away. However, humans are the biggest source of biological

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erosion. We cause erosion when we clear fields of abundant trees to begin new construction. The amount of damage we cause when we clear land and other areas to build new developments would take our animal counterparts more than 100 years!

Do you think Earth has always looked the way it does now? Do you think glaciers always stay the same size and shape? Where are volcanoes found? Where do earthquakes happen? Is the ocean floor completely flat?

Actually, plate tectonics are constantly making the land move. The shifting of the plates is what causes earthquakes. Earthquakes can occur anywhere the plates shift. Some areas are just more prone to them.

Glaciers are constantly moving and melting.

Volcanoes are found in many places around the world.

The ocean floor has features such as mountains and valleys just like we see on land.

Top view of melting glacier

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Your child has been learning about destructive and constructive forces. How can a force be both destructive and constructive at the same time?

Read about and look at pictures about volcanoes. Pick one volcano to focus on. What caused this volcano to form?

What impact do volcanic eruptions have on Earth? What happens to the people who live close to these eruptions? Volcanoes are destructive forces. How can they be constructive as well? One way is the formation of the Hawaiian Islands.

Research the newest island of the Hawaiian Islands. Has this been a constructive formation?

Make your own volcano! Use sand, soil (like potting soil), and water to form a “mountain.” It may help to build it up around something like a plastic cup. Measure the height and circumference of the volcano. Record the measurements.

Inside the cup, mix a half box of baking soda, a tablespoon of dishwashing liquid, and about 10–12 drops of red food dye.

Pour enough vinegar into the cup to watch the “lava” run down the mountain!

Let the lava dry overnight. The next day, measure and record the height and circumference of the volcano. Record and compare the differences between the measurements. Do the same process over the next several days. You should be able to see how constant eruptions of a volcano change the way the mountain looks as well as the land surrounding it.

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