What is Erosion?
[[File:Gully in the Kharkov region.jpg|thumb|right|230px|Erosion has removed [[soil]] from this [[forest]] in [[Kharkiv Oblast]], [[Ukraine]].]] '''Erosion''' is a process where natural forces like [[water]], [[wind]], [[ice]], and [[gravity]] transport [[rocks]] and [[soil]]. It is a [[geological]] process, and part of the [[rock cycle]]. Erosion occurs at the Earth's surface, and has no effect on the [[Earth's mantle]] and [[Earth's core|core]]. Most of the [[energy]] that makes erosion happen is provided by the [[Sun]]. The Sun's energy causes the movement of water and ice in the [[water cycle]] and the movement of air to create wind. Erosion can cause problems that affect humans. [[Soil erosion]], for example, can create problems for farmers. Soil erosion can remove soil, leaving a thin layer or rocky soil behind. Erosion can also cause problems for humans by removing rocks or soil that support buildings. Erosion can be caused by natural elements such as wind and ice. == Erosion by water == [[File:Regenerosion offenerBoden Tagebau.jpg|thumb|right|230px|Water moving downhill can carry away pieces of rock and soil]] Temperature changes cause pieces of rock to flake away from the surface. Also, the [[acid]] in rainwater dissolves rocks containing [[calcium carbonate]]. These processes are called [[weathering]]. Water erosion happens when water moves the pieces of rock or soil downhill. [[Waves]] also carry away small pieces of material. A wave can wash up onto the surface of rock or soil and then carry away pieces of material as it flows back into the [[ocean]] or [[lake]]. The size of earth materials that can be moved by water depends on how fast the water is moving. A fast-flowing stream can carry large rocks while a slow-moving stream might only be able to carry very small things like [[clay]]. [[Canyon]]s are among the most obvious features made by erosion. Where a river meets the sea, it drops the solids, sometimes making a [[river delta]]. === Tropical rivers === [[File:Amazonrivermap.svg|thu