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Erosion - Southern China
Did you ever wonder what is erosion? The dry, technical definition is the process by which the surface of the Earth gets worn down. Erosion can be caused by natural elements such as wind, gravity, glacial ice, or water. Erosion is the reason that valleys form, rivers are muddy after it rains, and the rocks at the bottom of a river are round. You want to see extreme examples of erosion, look at deep valleys that have rivers at their bottoms. Millions of years ago, that river was at the top of the valley that it cut. Erosion is a natural process that occurs on many objects in the universe, but here on Earth it has been dramatically sped up by mankind.
When rock and sediments move down hill it is called mass wasting. This is mainly due to gravity. Mass movement is an important part of the erosional process. Mass wasting occurs continuously on all slopes. When it happens quickly(mudslides, landslides) it can have disastrous results. One of the visible topographical manifestations of a very slow form of this phenomena is a scree slope.
Erosion by water can happen in many different ways: splash erosion, sheet erosion, rill erosion, gully erosion, bank erosion, and shoreline erosion are the main types. As water flows, it picks up sediment particles. The different types of water erosion all refer to how the water flows across and works on the soil.
Wind erosion mainly occurs in arid climates. The wind picks up grains of soil(sand usually. The wind will blast that sand across the surface of the earth and exposed rocks, eroding them into different shapes and patterns.
Thermal erosion works mainly on permafrost. The permafrost is weakened by melting underneath caused by running water below. Usually, what happens is that the banks of rivers fall collapse in large portions.
Many weather factors cause erosion to occur. Mankind is the largest contributor as we deforest and till larger portions of our planet. Can you think of a solution?
We have written many articles about erosion for Universe Today. Here are some soil erosion pictures.
If you’d like more info on Erosion, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.
We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.
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