Weathering, erosion and deposition form part of Earth’s geologic cycle to alter and transform its surface. Erosion occurs when mechanically or chemically soft rock is broken apart by wind, water or ice and carried away to form new soil formation.
Pollution-derived acid rain quickly wears away at limestone, marble and other stone materials – as evidenced by Apple Rock near New Zealand or beaches with black sand beaches.
Weathering
Weathering and erosion are ever-present phenomena, from cracks in sidewalks to the beach sand eroding away to rocks rolling off mountains. Their effects continue to shape Earth’s landscape as weathering and erosion work to alter it over time.
Weathering, either physically or mechanically, breaks rocks down into smaller pieces over time. Rain and wind play an integral role in this process – they help wash away beach sand or cut through canyon walls by dislodging their surfaces.
Chemical weathering can also play a part in breaking down rocks. Iron in certain rocks interacts with oxygen to form rust that chips away at or crumbles the rock surface. Water entering cracks or pores of rocks swells them up and can subsequently break them apart.
Gravity then transports these particles to their new destination – known as deposition – which may happen quickly, like with a landslide, or slower such as sediment flowing down rivers.
Erosion
Weathering and erosion work to shape Earth’s rocks into ever-evolving works of art. You can see these processes at work everywhere from beach sands to rivers carving through mountains to form canyons.
Les loosened particles of rock that are carried by water, wind or glacial ice and transported are known as sediments; when they arrive at their destination they are known as deposition.
Erosion can be affected by factors like rainfall intensity and amount, temperature, humidity, seasonality, wind speed and direction, vegetation cover and human activities like deforestation, roads or industrial agriculture that loosen soil particles for transporting. Other forms of erosion are caused by avalanches and landslides.
Deposition
Sand on beaches forms from the gradual accumulation of fine particles eroded away by wind erosion. This process occurs over time.
Chemical weathering differs from mechanical weathering (splitting), in that it weakens or alters the composition of rock. This makes it easier for other forces to break it apart; especially prevalent in warm locations where temperature allows water to penetrate cracks in rocks and expand them; plant roots are another potential cause.
Weathering and erosion work together to create breathtaking natural sculptures, but they can also be harmful. Erosion can carry away soils that contain hazardous chemicals into lakes or rivers; expose dangerous underground coal seams; wash away important farmlands needed for food production; expose dangerous underground coal seams; expose dangerous underground coal seams; wash away vital farmlands that provide essential food sources and more.
Deltas
As water breaks down rocks, it transports particles away through erosion. Erosion may be caused by weathering or living organisms such as plant roots which wedge their way into small cracks in rocks to cause further wear-and-tear, while eventually the pieces of rock created are carried away by either wind or water into new locations.
Deltas form when rivers deposit more sediment at coastal locations than is removed by tides and waves, creating distinctive triangular shapes in planar view known as deltas (from Greek for “delta”). The world’s largest delta is found between Bangladesh and India and sustains fisheries as well as crops such as tea and rice production; unfortunately human actions are depriving these deltas of needed silt to combat land loss and subsidence.
Oxbow Lakes & Meanders
A meander is a bend or curve in a river that makes an S-shape around its valley floor, where fast moving water erodes away sediment to form river cliffs on either side. Ongoing erosion in this inner portion allows less sediment accumulation, leading to slower flow rates of sediment into it over time and eventually leading to gradual inward bends called meander necks.
Erosion at the neck of a meander narrows its neck until, over time, it separates completely from its main river channel and forms an oxbow lake that doesn’t have an natural outlet but provides wildlife with habitat and attracts birds and other forms of life. Over time it may fill with silt or dry up as water evaporates away resulting in silt build-up or drying up completely over time.