How Do Erosion & Deposition Help Make Thick Soils?

Erosion

• Over thousands or even millions of years, erosion creates major physical changes on the face of the Earth. Magnificent features like the Grand Canyon and the Mojave Desert are a direct result of erosive forces removing soil and rock or breaking it down into smaller pieces. But this loose soil and bits of rock don't stay in motion forever. They have to land somewhere, and when they do, soil begins to build up in thicker layers. Erosion is a constant force that can be influenced by human development, but never completely controlled.

Process

• Geologists break down erosion into three stages, known as detachment, entrainment, and transport. Though independently categorized, sometimes the lines between these stages blur. Erosion begins with detachment, defined as a particle breaking free from a larger solid. Entrainment is the process by which the particle is lifted by the erosive force, commonly water or wind. Transport occurs after the particle is entrained and under the control of the force. This is the stage that causes relocation.

Deposition

• Particles in transport continue until the velocity of the erosive force weakens to the extent that gravity causes the particle to fall back to the gtound. This is called deposition. Due to various factors, deposition tends to occur in certain areas. For example, look at rivers, which snake back and forth rather than run straight. These bends are prime deposition areas where soil collects and grows thick. Over the millennia, these become flood plains, which yield some of the best crop-growing media around.

Considerations

• Keep in mind that a single particle might find itself in repeated cycles of erosion and deposition before it finds a relatively secure resting spot. The weight, size, and shape of the particle are some of the determining factors regarding how long it stays in transport and exactly when deposition occurs. It is interesting to consider that no deposition spot is ever permanent. The Earth's surface is constantly being re-shaped into new configurations, and the thick soil of today could be destined to be the thin soil of tomorrow.