Weathering erosion and deposition are two processes that constantly shape Earth’s surface, whether slowly as cracks appear in roads and sidewalks or rapidly like mudslides.
Weathering breaks up rock into smaller pieces without moving them; erosion transports or displaces these rocks from their original locations and deposits them elsewhere.
Water
Water and wind are among the primary forces responsible for moving rocks and soil from one location to the next, known as erosion. Erosion has had a profound effect on Earth’s landscape and created landmarks such as Grand Canyon.
Water is a powerful solvent, or substance which dissolves other materials, capable of breaking down rocks and minerals over time.
Physical weathering erodes rocks by crushing or breaking them apart through rain, wind and other atmospheric forces.
Chemical weathering is the gradual chemical breakdown of rock material through exposure to acid from human activities or naturally occurring sources, such as carbonic acid. Acids can weaken or dissolve rocks; chemical weathering often produces clay as an end product. Silica (an ingredient of glass and cement), is another by-product.
Wind
Wind can have an enormous impact on weathering erosion and deposition processes, moving soil particles around and creating sand dunes on beaches or desert landscapes. Furthermore, it can smooth rocks and cliffs to give them their signature “desert varnish” finish color.
Wind erosion is usually slow; it takes years for one rock to be worn away by wind erosion. But sometimes it happens quickly, such as during mudslides or sudden drops in waterfalls.
Erosion can be both helpful and harmful; it can make trails or roads more accessible while carrying hazardous chemicals from farms and industry into rivers and streams, wear down rock surfaces to form caves, as well as deposit sediment such as sand, silt and gravel in places where it’s needed – this process is known as deposition; whether through wind, rain or ice or gravity as it flows downhill it could happen nearby or miles away in rivers.
Glaciers
As glaciers move, they bring with them rocks and sediment that erode underlying surfaces while shaping the landscape. Most glaciers around the world have negative mass balances – meaning that they are retreating.
Over time, snow on top of glaciers begins to accumulate and become heavier than that on bottom, eventually compacting into dense ice that becomes dangerous if dammed to streams or rivers, such as when Hubbard Glacier surged in Alaska in 1986 and blocked Russell Fjord from accessing the ocean. This process is known as compaction, and can become particularly hazardous when damming occurs with rivers like Hubbard did when it surged and blocked Russell Fjord from accessing it.
As glaciers melt, they deposit all the rock fragments they’ve carried along in a pile known as a moraine. Additionally, when glaciers move past certain locations they sometimes drop large boulders called erratics which may seem out-of-place but give geologists insights into ancient glacier movements.
Deposition
Deposition refers to the process by which natural forces transport weathered material from one place to another, typically by gravity, running water, glaciers or wind currents. The material transported during deposition is known as sediment. River erosion shapes the landscape by transporting sand and rock particles that become sedimentary rock that forms into gorges, flood plains or cliffs in its wake.
Physical weathering occurs when rocks change their shapes without altering their chemical makeup, leading to landside slides and mass wasting, often in tandem with erosion. Plant growth may also contribute to physical weathering by breaking apart rocks into fragments with cracks and crevices forming across their surfaces.
Chemical weathering occurs when acidic waters erode certain types of rock, such as limestone. This process often leads to caves and sinkholes being created. Erosion may happen gradually over time such as at the Grand Canyon or quickly like during a mudslide; all forms of erosion form part of a cycle which has existed for billions of years.