Weathering & Erosion Choose OK

What is weathering? Weathering is the process that breaks down rock and other substances on Earth’s surface. The forces of weathering breaks rocks into smaller and smaller pieces

What is Erosion? Erosion is the removal of these small particles of rock by wind, water ice or gravity. Erosion is the removal of these small particles of rock by wind, water ice or gravity. Weathering and erosion work together to continuously wear down and carry away the particles, constantly changing the surface of Earth. Weathering and erosion work together to continuously wear down and carry away the particles, constantly changing the surface of Earth.

There are two main types of weathering: Mechanical [sometimes called physical] Mechanical [sometimes called physical] Chemical Chemical Both types of weathering act slowly, but over time, they break down even the biggest, hardest rocks.

Mechanical weathering breaks rocks down into smaller pieces. Types of mechanical weathering include freezing and thawing, release of pressure, pant growth, actions of animals and abrasion.

Let’s investigate mechanical weathering first.

In mechanical weathering, a rock is broken down into smaller pieces without changing its mineral composition.

There are several different processes that cause mechanical weathering. View Website View Website

Observe the effects of mechanical weathering View Website View Website

Enchanted rock is a huge example of mechanical weathering.

Now, let’s look at chemical weathering.

Chemical weathering breaks rocks down rock through chemical changes. The causes of chemical weathering include: WaterOxygen Carbon dioxide Living Organisms Acid Rain

Chemical weathering happens when the minerals that make up a rock are changed, leading to the disintegration of the rock

EXAMPLES OF CHEMICAL WEATHERING OXIDATION OCCURS when free oxygen combines chemically with metallic elements (usually iron) OXIDATION OCCURS when free oxygen combines chemically with metallic elements (usually iron) AKA RUST AKA RUST

CARBONATION Water containing carbonic acid dissolves minerals (all rain water is slightly acidic) Most strongly affected are calcite minerals: Most strongly affected are calcite minerals: limestone and marble limestone and marble

CARBONATION Stalagmites and stalactites Stalagmites and stalactites

Acid Rain Acid rain causes rapid chemical weathering Acid rain causes rapid chemical weathering

Lichens on rocks cause chemical weathering by secreting an acid that breaks down the rock.

View the following websites to learn more about chemical weathering 1.) Feldspar to clay 1.) Feldspar to clayFeldspar to clayFeldspar to clay

Now let’s move on to EROSION

What is erosion? Erosion is the process by which natural forces move weathered rock and soil from one place to another. Some of these forces include glaciers, wind, water, earthquakes, volcanoes, tornadoes, hurricanes, mud flows, and avalanches.

As soon as a rock particle (loosened by one of the two weathering processes) moves, we call it erosion. As soon as a rock particle (loosened by one of the two weathering processes) moves, we call it erosion. When it comes to rest, or lay down, we call it deposition. Weathering, erosion, and deposition act together in a cycle that wears down and build up Earth’s surface.

Water is the most important erosional agent and erodes most often as running water in streams or rivers.

Flooding

Sea Arches

Beach Erosion

River Erosion

Observe river erosion causing waterfalls Visit this website website

Waves in oceans and other large bodies of water cause coastal erosion. The power of ocean waves is awesome; large storm waves can produce 2000 pounds of pressure per square foot. The pure energy of waves along with the chemical content of the water is what erodes the rock of the coastline.

Wave action in Calvert County Maryland

Watch wave erosion on this website website

Erosion by wind is known as aeolian erosion (named after Aeolus, the Greek god of winds) and usually occurs in deserts. Aeolian erosion of sand in the desert is partially responsible for the formation of sand dunes.

Painted Desert National Monument

Sahara Desert

Gobi Desert in China

Kalahari Desert

Dust Bowl, the man-caused environmental disaster of the 1930s

The erosive power of moving ice is actually a greater than the power of water. However since water is much more common, it is responsible for a greater amount of erosion on the earth's surface.

Athabasca Glacier - Jasper, Canada

Hubbard Glacier in Alaska

valley glacier

Observe landscapes formed by erosion click on the website website

Let’s look at some more examples of erosion. Website

The End!