Erosion is the movement of soil, mud, rock by wind, water or ice. Erosion can happen over a long period of time or can happen suddenly with flooding or other natural disasters. Erosion is distinguished from weathering, which is the break-up of large and small rocks.

Erosion happens naturally all around the earth. A certain amount of erosion is natural and healthy for the ecosystem. For example, gravels continually move downstream in watercourses.

Excessive erosion, however, can cause problems such as when small particles of dirt and rock are washed into rivers, it can cause the water to have less oxygen then normal and can kill the fish and wild life.

Nature will control erosion by the way that plants grow on hillsides and along streambeds. The roots of these plants hold the soil in place and keep the water from pushing the soil and vegetation out of place. If the plants are left to grow on their own they will keep the soil in place.

Evidence of erosion- This is a picture of the White River on the eastern side of Decatur Township.  Do you see signs of erosion? Here are some Signs of erosion may often be seen in a river. Look for one or more of these signs: Exposed tree roots. Cracks in the soil in a river bank. Clumps of grass in the river. The top part of the river bank overhangs. Brown or coloured water. Collapsed river bank.

Causes for Erosion

Lack of Ground cover- One of the biggest factors that causes erosion is the lack of plants or groundcover. When fires burn an area or when vegetation is removed as part of cutting timber or in this case the land fill, the ground is more likely to have problems with erosion.

Wind- Wind erosion devastates farmland all over the world. Dust and sand storms are the most common forms of wind erosion.  When there are no plants to help keep the soil in place, farmers watch helplessly as their top soil is blown away by the wind

Waves cause erosion by four different methods: Breaking – as the breaking waves hit the shoreline, their force knocks off pieces of existing rocks. Forcing water into the cracks of the rocks on the shoreline Abrasion- waves carry small rocks and sand that scrape other rocks Chemical weathering (salt water breaks down the rocks) Factors that affect the rate of erosion at the shoreline include: Size of the waves Force of the waves Type of the rock

Glacial Ice- A Glacier is a large body of ice that is  slowly moving across the land, pushing sand and rocks as it moves.  There are only a few active glaciers in the United States. For glaciers to be active, there must be constant snow and ice and that only happens in the furthers regions of the country such as Montana and Alaska. Although there are not a lot of active glaciers in our country, we can definitely see the results of their movement. Glaciers is responsible for the formation of Long Island in New York and the Great Lakes here in the Midwest.

Chemical Erosion caused by Acid Rain- A type of erosion that is not as easily seen is that caused by acid rain.  This is where pollution from cars and factories give off poisonous chemicals into the air and those chemicals fall on the land as polluted rain.  One of the most interesting ways of seeing this is to look at statues throughout the city or go to a cemetery and look at the headstones.  You will see black marks and it is very difficult to read the writing on the stones.  Through the years, these chemicals have eaten away the stone so you can't see the writing.  If the air pollution continues and we do not control the bad air that is given off by cars and factories, we will loose these stones forever.

Difference between Erosion and Weathering

Weathering involves two processes that often work together to break down rocks. Both processes occur without moving the rock so there is no movement in weathering. It’s important to keep in mind that weathering happens on top of the rock or very near the surface.

Erosion- As soon as a rock are small enough to be moved by water, wind, rain or ice it is called erosion. The rocks are loosened by one of the two weathering processes. Erosion, which is also called Mass wasting, is simply movement down slope due to gravity. Rock falls, slumps, and debris flows are all examples of mass wasting. We call it erosion if the rock particle is moved by some flowing agent such as air, water or ice.

How can man help control erosion?  There are many ways that man can help control erosion.  One way is right here in Decatur Township with our levee. Many of the residents that live in the White River Flood plane have created their own levee system by putting large pieces of concrete from building projects along the West band of the river.  This has kept the river from breaking the levee at this point for many years.

Control Deforestation- It is very important for all humans to protect trees. We need trees to build homes, make furniture and paper, but logging (cutting down trees) must take only a few trees at a time.  Also it is important that for every tree that is cut down, another one is planted in it's place.  This will not only take care of erosion, but it will also help with global warming.

Not Overgrazing- All ranch animals such as horses, sheep, cows and goats need grass to eat.  That is their main source of food.  However, it is very important to make sure that animals are moved around so that they do not eat the grasses down to the roots or even pull out the roots.  Farmers must rotate their animals throughout many fields or give the plants a rest by supplying hay for the animals to eat.  This will make sure that the plants do not die and as the plants decompose their roots loosen and the wind and water can cause the topsoil to be washed or blown away.

Be Careful with Road Construction- As new roads are built is is very important for grass seed and straw to be put on the ground so the seeds have a chance to germinate (grow roots down into the ground).  The straw placed on top of the seeds will keep the wind and rain from washing the seeds away and within a week or two, grass should be growing and will keep the topsoil in place.

Web resources

www.kozgro.com

National Parks Service