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Weathering and Erosion Delta Science Reader

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Weathering and Erosion Delta Science Reader

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Go to Brainpop on Classlink, and search for Weathering, and Erosion videos.

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Weathering is the breaking down of Rock (geology) rocks, soil and their minerals through direct contact with the Earth's atmosphere, waters, or living things. It is a natural process.

Weathering occurs in one place with little or no movement, and should not be confused with erosion which is when rocks and minerals are moved to another place by ice, water, wind or gravity.

Mechanical weathering

Mechanical or physical weathering is when the rocks and minerals are broken down but the Chemical composition remains the same. Mechanical weathering physically breaks up rock.

Wind can blow water or small particles such as sand against the rock thus breaking it down. The wind blowing over your skin removes body heat.local winds are the winds that blow over short distances.

Rain is another force that works slowly. The force of raindrops on some rocks make them wear down. Rain also can make a chemical change in some rocks, because it is usually slightly acidic. The water mixes with the minerals in the rock to break it down.

Temperature

Changing temperature can make a rock crack. Every day when the sun shines on the rock, its surface is heated. Heat causes the surface to expand (get bigger) a little. The inside of the rock, though, does not heat up as fast as the outside of the rock. The inside of the rock stays cooler. At night, the surface cools down and contracts. The expanding and contracting makes some places on the surface weak, and a crack is made.

Also, if water gets into a crack in a rock and the temperature goes below the freezing point, the water will freeze and expand. After some time, the rock may be weak enough to break into pieces.

Ice, which can be miles thick, grinds the surface of the rock below it. The particles are carried with the ice, and if a glacier ends up in the sea, so does all the material carried with it.

Lava or magma

Lava or magma can cause weathering when molten rock touches older rock. It causes the older rock to change form to a different crystal structure.

Chemical weathering

Chemical weathering is the breaking down of rock which changes the chemical composition.

Carbon dioxide cycle

The carbon dioxide cycle is the most important for weathering. CO ₂ is put into the atmosphere mostly by volcanoes, and it is taken out of the atmosphere by photosynthesis, and by one other process.

While it is in the air, CO ₂ can dissolve in water droplets to form weak carbonic acid.

When rain hits rock it does so with mechanical energy and dilute acid. The acid dissolves many types of minerals and rocks though, of course, very slowly. When a mineral like feldspar is dissolved, it lets sodium ions into the sea; chlorine ions come from other minerals. The sea tastes salty because of the elements which have been dissolved out of rocks.

Related pages

Images for kids

Wave action and water chemistry lead to structural failure in exposed rocks.

Pressure release could have caused the exfoliated granite sheets shown in the picture.

Weathering effect on a sandstone statue in Dresden, Germany.

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Weathering is the breaking down of Rock (geology) rocks, soil and their minerals through direct contact with the Earth's atmosphere, waters, or living things. It is a natural process. Weathering occurs in one place with little or no movement, and should not be confused with erosion which is when rocks and minerals are moved to another place by ice, water, wind or gravity.

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Main content

This stream is carrying out erosion. Erosion is a process by which earth materials, such as weathered rock and soil particles, are moved from one place to another. There are many different ways earth materials are transported. These different ways are referred to as agents of erosion. Let's take a closer look at some examples of agents of erosion. This glass of water was taken from this rushing river. Notice how dirty the water looks? If we let the glass sit still for a few hours, the sediments settle to the bottom. You decide. Where did the sediment come from?

As water moves across the surface of land in a process called run off, it carries sediments into rivers and other bodies of water. Moving water is the most common powerful agent of erosion. Rivers, streams, and creeks are examples of moving water. It's estimated that the Mississippi River transports over five hundred million tons of sediment each year. Waves are the major force of erosion along coasts. At this very moment, waves on this beach are transporting tons of sand, steadily moving it along the coast. Wind is also a significant agent of erosion. Wind can carry large amounts of sediments, including sand. In Death Valley, California strong winds move sand particles, which are deposited here forming sand dunes. This large field of ice and snow is a glazier. Glaziers are actually moving sheets of ice and snow. As glaziers slowly move they carry out erosion by moving fragments of rock, boulders and other debris. The dirt's you see here is actually sediments eroded by the glazier. When parts of the glazier melt, large deposits of rock, boulders and sediment are formed.

Source Citation

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This stream is carrying out erosion. Erosion is a process by which earth materials, such as weathered rock and soil particles, are moved from one place to another. There are many different ways earth materials are transported. These different ways are referred to as agents of erosion.

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Field After Landslide

Words to Know

Erosion makes rocks and soil move. Wind and water can make erosion happen. It can happen for other reasons, too.

Erosion happens because rocks break into pieces. The small pieces then move.

Erosion changes Earth's surface. It changes mountains. It changes beaches.

Erosion is powerful and important.

What Is It?

Erosion happens because rocks break into pieces. This called weathering.

Weather can happen for many reasons. Rocks can break down because of water or ice. They can break down because people step on them. They can break down because of hot weather.

Weathering makes tiny pieces of rock. Erosion moves those tiny pieces.

The tiny pieces travel to other places. They settle in new places. This is called deposition.

Why Does It Happen?

Erosion happens in different ways. Water causes erosion. Water is powerful. It can move soil and rock. This is erosion.

Erosion happens because of wind. Wind can pick up small pieces of dirt or rock. Wind can blow the dirt or rock far away. This is also erosion.

Erosion can also happen when rocks fall. Earth has a force called gravity. Gravity holds people and things on Earth's surface. It also causes people and things to fall. Some rocks fall and move. This is erosion, too. It happens because of gravity.

What Does It Do?

Erosion changes Earth's surface. Erosion can change the shape of beaches. It can also change the shape of mountains and other landforms.

Erosion also moves dirt. This can make growing crops difficult. Erosion can be harmful to farmers and people who grow crops.

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Field After Landslide Erosion makes rocks and soil move. Wind and water can make erosion happen. It can happen for other reasons, too. Erosion happens because rocks break into pieces. The small pieces then move. Erosion changes Earth's surface. It changes mountains. It changes beaches. Erosion is powerful and important.

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Main content

The rocks on this beach were not always smooth and round. You decide. How did these rocks get so smooth and round?

Over many, many years, the action of waves and the process of rocks rubbing against each other caused them to become rounded. Over time, the rocks also became smaller. Weathering is the process responsible for breaking down rocks and other materials on Earth's surface into smaller and smaller pieces. Some agents of weathering include moving water, ice, and even chemicals in rainwater. The Grand Canyon, which is nearly a mile deep, has been worn down over millions of years by weathering. The Colorado River at the bottom of the canyon is responsible for carrying away materials weathered from the canyon walls. Erosion is the process of transporting weathered rocks, particles, and sediments from one place to another. So, through the process of weathering and erosion, rocks are broken down into smaller and smaller pieces which are then carried away by moving water, wind, or other forces to another place.

Source Citation

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The rocks on this beach were not always smooth and round. You decide. How did these rocks get so smooth and round? Over many, many years, the action of waves and the process of rocks rubbing against each other caused them to become rounded. Over time, the rocks also became smaller.

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Article Reading Levels

Level 3

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Main content

Weathering is a natural process that slowly breaks apart or changes rock. Heat, water, wind, living things, and other natural forces cause weathering.

Weathering created an arch of rock on the coast of England.

Over many years, weathering can shape rock into unusual formations. Weathering is responsible for many rock arches and hoodoos (lumpy columns), such as those found in Utah's Arches and Bryce Canyon national parks. Weathering also has shaped the slabs of limestone in the Burren in Ireland.

Weathering and Erosion

Weathering is related to erosion, which is the wearing away of rock and earth by natural forces. However, erosion generally means that bits of rock and earth are carried away from their original location. By contrast, weathering leaves the main area of rock in place.

Types of Weathering

The forces that cause weathering may be physical, chemical, or biological. Often, weathering results from a combination of forces.

Physical forces include changes in temperature or pressure, freezing or moving water, and wind. An increase in temperature may cause rock to expand. As the rock cools, it contracts, or shrinks. The expanding and contracting may cause the rock to crack and break apart. If heavy material on top of a rock is removed (by a glacier, for example), the pressure on the rock decreases. The release of pressure may cause the rock to split. Water that freezes inside cracks in a rock may widen the cracks. Particles carried by water or wind may slowly scrape away a rock's surface.

In chemical weathering, the minerals that make up the rock are changed. Water usually is involved in chemical weathering. Elements in the water may react with the minerals in the rock. The minerals may break down or form different minerals.

Biological weathering results from the actions of living things. The roots of plants may reach inside rock openings. Over time, they may push apart sections of rock. Lichens grow on rock surfaces or within cracks. They may wear down rock or etch patterns on its surface.

Source Citation

Gale Document Number: GALE|USMUGZ113072791

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Article Reading Levels Level 3 Document controls Citation metadata Weathering is a natural process that slowly breaks apart or changes rock. Heat, water, wind, living things, and other natural forces cause weathering. Weathering created an arch of rock on the coast of England. Over many years, weathering can shape rock into unusual formations.

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Go to Pebble Go and search the word Erosion.