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Weathering is the process of breaking down rocks into smaller pieces called sediment. This sediment further breaks down and becomes soil. This article explores the different types of weathering, such as mechanical and chemical weathering, as well as the agents of erosion, including wind, water, glaciers, and gravity. It also discusses the various forms of erosion, such as wind erosion, water erosion, glaciers erosion, and gravity/mass movement erosion, including slump, creep, rockfalls, rockslides, mudflows, and landslides. The article concludes with a discussion on deposition and the formation of landforms such as deltas, alluvial fans, moraines, sand dunes, and sandbars.
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WeatheringThe process of breaking down of rocks into smaller and smaller pieces of rock. These small pieces are known as sediment. Sediment breaks down further and becomes soil. YehliuTaiwan-HoneycombWeathering 180px-GeologicalExfoliationOfGraniteRock
Types of Weathering • Mechanical/ Physical Weathering • Chemical Weathering
Types of Mechanical Weathering The process of breaking down of rocks and soils by a physical force • Ice Wedging- Water in the cracks of rocks freeze • Abrasion- Particles of sand are carried by the wind and water • Plant Action – roots from plants grow in the cracks of rocks • Release pressure – when pressure is removed from rocks
Chemical Weathering The process in which the chemical makeup of a rock is changed by a chemical reaction. http://en.wikipedia.org/wiki/Weathering#Chemical_weathering
Types of Chemical Weathering • Oxidation – a chemical change that occurs with oxygen. Iron and Oxygen form rust • Acids – natural acids break down rock. http://en.wikipedia.org/wiki/Stalagmite
Erosion • Erosion takes rocks and other particles from one location and puts them in another. • Weathering is breaking up rocks erosion is carrying them away.
The Agents of Erosion • Wind • Water • Glaciers • Gravity / Mass Movement
Wind Erosion • Wind can carry sand, silt, and clay from one place and deposit it in another. • This type of erosion is most frequent in dry areas with little or no vegetation.
Wind Erosion http://upload.wikimedia.org/wikipedia/en/1/15/Mesquite_Sand_Dunes.JPG
Water Erosion • The most significant agent of erosion is running water. • Water runs down hill and form a gully by taking away sediment. • Water continues to flow in the gully and eventually forming a valley. • Water can cause erosion of the shore line can be from waves in the ocean.
Water Erosion http://en.wikipedia.org/wiki/Image:Gully_ElPasoCounty_CO_USA.jpg
Water Erosion http://en.wikipedia.org/wiki/Image:Wavecut_platform_southerndown_pano.jpg
Glaciers Erosion • Glacier Erosion is sometimes referred to as Ice Erosion • Glaciers move slowly across land picking up large rocks and even larger boulders. • Glaciers can cause deep valleys to form as they move across the land.
Glaciers Erosion http://en.wikipedia.org/wiki/Image:Glacier_mouth.jpg
Gravity/Mass Movement Erosion • Gravity is the force behind Water and Glacier Erosion • Gravity alone can cause Erosion
Gravity/Mass Movement Erosion http://en.wikipedia.org/wiki/Erosion#Gravity_erosion
Types of Gravity/Mass Movement Erosion • Slump • Creep • Rockfalls • Rockslides • Mudflows • Landslides
Slump • A slump occurs when a mass of land slips and moves down a slope. • A slump occurs when the slope becomes too steep and the material under it can not support the ground above it. http://geology.about.com/library/bl/images/blslump.htm http://geology.about.com/library/bl/images/blslump.htm
Creep • Sediment slowly moves down hill. • Leaning trees and fence post are clues that creeping is occurring
Rockfalls Occur when parts of a rock break off and tumble through the air. http://www.seismo.ethz.ch/hazard/risk/PaleoSeis/rockfalls2.htm
Rockslides • Large and small rock slide down a slope. http://www.grisda.org/origins/11090.htm
Mudflows • Happen after heavy rains. • More likely to occur when there is a lack of vegetation. • Gravity pulls on the heavy water saturated sediment and causes it to flow down hill. http://en.wikipedia.org/wiki/Image:Mudflow_mailboxes.jpg
Landslides • A movement of land down a slope. http://www.signonsandiego.com/news/state/20050601-1811-wst-lagunalandslide.html
Deposition • Process by which sediments, soil and rocks are added to a landform or land mass (the end of erosion). http://education.usgs.gov/lessons/schoolyard/RockSedimentary.html
Deltas – forms from deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment.
Alluvial Fan - a fan-shaped mass of alluvium deposited as the flow of a river decreases in velocity.
Morains - a mass of rocks and sediment carried down and deposited by a glacier, typically as ridges at its edges or extremity.
Sand Dune - hill composed of sand, formed by the wind. Dunes can also form underwater by the action of waves and currents.
Sandbar - an area of sand, gravel or fine sediment that sits above the water. It may be connected to the shoreline, or it may be offshore. It is generally narrow and straight. A sandbar is also known as a shoal or sandbank.
