Erosion and deposition are processes that alter the surface of Earth over time, and occur naturally when gravity, ice, wind or water lose their energy and stop transporting rock particles along their course.
Physical erosion occurs when rocks erode through their surfaces, producing clastic sediments which then act like an erosion agent to form landslides or mass wasting along ridgelines.
Water erosion is one of the principal forces shaping Earth’s landscape, moving soil particles down from steep slopes into rivers, lakes, or oceans – leading to their subsequent transport into bodies of water as rivers flow from their basins into them. Furthermore, erosion caused by water can cause rocks to wear down and break apart through weathering processes; all of this together has led to its widespread presence across Earth’s terrain.
Speed of water flow impacts how much erosion takes place; faster-moving waters erode rock and soil more quickly than slower moving waters, leading mountain streams to carve narrow V-shaped valleys while river currents shape broad floodplains with curving meanders called meanders.
Once sediment has been carried away by flowing water, it begins to settle out. Over time, as sediment drops away it forms layers called alluvial fans or deltas; eventually these build up along coasts as natural levees to provide protection from powerful storm surges and waves.
Soil is an invaluable natural resource that is home to an astonishing range of living things. Composed primarily of minerals, organic matter from deceased and living organisms, air, and water, its physical and chemical properties are affected by many natural processes, including weathering, erosion, and deposition.
Soil erosion can be caused by natural forces like extreme rainfall, floods and windstorms as well as human activities like mining or unsustainable agriculture, which disturb topsoil layers reducing its resistance to runoff and soil loss.
Erosion’s primary impact is to reduce soil productivity. Poorly managed agricultural fields that expose their topsoils to erosion often experience reduced crop yields as a result. Furthermore, eroded particles may clog streams and lakes affecting water currents while the loss of quality structure and texture hamper seed germination and buries small plants, restricting their growth requiring replanting in some cases; furthermore it affects biodiversity leading to some species going extinct altogether.
Vegetation covers nearly the entirety of our planet and serves numerous key purposes, from regulating biogeochemical cycles such as water, carbon and nitrogen cycle flow to providing local and global energy balance contributions and habitat for both plants and animals.
Vegetation helps mitigate erosion by adhering to rocks and soil particles and trapping wind, but losing vegetation may trigger mass-wasting events like landslides that bury millions of tons of material beneath the surface.
Physical erosion has the power to create some of the Earth’s most remarkable features, from caves carved into rock cliffs to the towering sea stacks found throughout Victoria, Australia. Erosion also creates sea arches – where waves batter away at rocks until all that remains are arches-shaped cavities in them.
Climate, topography and vegetation are the four primary elements that determine how much erosion occurs in any given landscape. Erosion tends to occur more in grasslands than agricultural fields because their plants’ roots help hold together soil particles.
Water erosion is often caused by high rainfall in areas that lack vegetation to mitigate it, particularly where there is no green cover present to slow its progression. Tree removal for agricultural purposes such as crop farming and ranching also increases erosion rates. Erosion caused by these activities can become an issue that leads to floods as well as runoff of fertilizers, pesticides and other chemicals into rivers and lakes.
Physical erosion carries away bits of the Earth while weathering breaks it down into its component rocks or dissolves it completely. When those bits of Earth are transported away by water, wind, or glacial ice they form sediment; deposits from which can range anywhere from being as close as topographical features to as far away as rivers and coasts.
Climate change is projected to accelerate erosion rates, especially in tropical regions where population growth and land conversion to agriculture have compounded erosion issues. Increased erosion can result in greater sediment loads entering streams and coastal ecosystems – disrupting bedrock weathering processes as well as contributing to global carbon cycling processes.