Erosion is the natural process of breaking down and weathering land. Boulders wear away into sand, while rivers erode mountains into valleys.
Water and wind erosion are major contributors to coastal degradation. Ocean waves pounding on coastlines erode coastlines into caves, stacks, and arches creating numerous coastal landscape features including caves.
Water erosion occurs when rain or other forms of liquid flow across rocks and soil loosen and carry material away, with most instances taking place during thunderstorms and floods. But erosion can also occur when soil has been over-drained excessively or during long droughts which leaves its surface dry and vulnerable to further erosion.
Physical erosion refers to any changes in the shape and texture of rocks without altering their chemical makeup, such as crumbling and dissolving rocks in mountainside collapses into ravines or waves crashing against coastlines, leading to formation of cliffs.
Climate factors that contribute to water erosion include rainfall amount and intensity, storm intensity and location. Furthermore, removing vegetation through intensive agriculture or deforestation reduces its ability to infiltrate into soil quickly thereby further increasing erosion rates.
Wind erosion refers to the movement of dirt, sand and rocks by wind currents. It is most frequently observed in desert environments as well as coastal beaches and dunes; it also poses problems in agricultural settings where crops and soil may be lost due to blow-off.
Sand particles light enough to be carried by wind can be transported and deposited elsewhere, where they may form sand dunes. Large rocks may also be broken apart by wind and other forces into smaller pieces that form canyons or mountains.
Erosion can be protected against by using plants as an armor against further erosion of surfaces in landscaped areas.
Erosion rates depend heavily on how humans have used and cultivated the land. Modern farming techniques using chemicals and machinery are likely to cause more erosion than more traditional approaches to crops and livestock grazing, leading to damage of natural vegetation as well as loss of nutrient from water bodies.
Glaciers are vast, snow-covered sheets of ice that cover large expanses of land, capable of altering entire landscapes by carving mountains, carving valleys and depositing massive quantities of rock and sediment.
Ice erosion differs from weathering, which wears down rocks without moving them. Weathering occurs when water seeps into cracks in rocks over time and eventually weakens them; plant roots can then wedge their way in through these openings and increase in size overtime, contributing to further erosion.
Glaciers move slowly over the land, collecting particles of dirt that they then carry away – a slow but powerful form of erosion. Glaciers carve up mountain valley bedstrews, creating U-shaped valleys, fjords and hanging valleys as they progress; glaciers also carve cirques – bowl-shaped depressions created by glaciers carving into mountains or valley sidewalls at higher elevations that often contain lakes known as tarns – that contain high-altitude lakes called tarns.
Erosion occurs as a result of human activities like tilling (plow) the soil before planting and growing crops, as this removes grasses and other ground-cover plants which keep soil together and leave it susceptible to wind, hard rains, and flowing water.
Water is one of the primary causes of erosion, carrying weathered rock and soil from one place to another – such as when rivers carry sediment from mountains into the ocean.
Water and ice can also contribute to erosion by breaking apart rocks or scraping away bits of rock from surfaces – this process is known as mechanical erosion.
Plants can help prevent erosion by binding to dirt, keeping it from washing away in rain and winds. But too much vegetation being removed from a land can increase erosion dramatically – this has become an issue in many regions where farmers clear forests to clear more land for livestock grazing purposes and overgraze livestock pastures.