Deposition, Weathering, and Erosion Weathering What Caused This?
http://commons.wikimedia.org/wiki/File:Toad_Rock_-_geograph.org.uk_-_76 7454.jpg http://en.wikipedia.org/wiki/File:KharazaArch.jpg Effects of Weathering
Weathering is a process that breaks down rock and other substances at Earths surface creates soil softer rock weathers faster weathering is fastest in hot and wet climates
Types of Weathering Mechanical Weathering Chemical Weathering What is Mechanical Weathering? Breakdown of rock into smaller pieces
without any change in the chemical composition of its minerals. Sometimes called physical weathering Rock is torn apart by physical force, rather than by chemical breakdown. Mechanical Weathering
Works very slowly There are different types ice wedging exfoliation thermal biotic
Mechanical - Ice Wedging Ice Wedging Water fills joints of rocks and freezes Freezing expands the water by 10% Repeated freeze and thaw cycles over the years causes rock to break
along joint Mechanical - Exfoliation Exfoliation or unloading Rock breaks off into leaves or sheets along joints which are
parallel to the ground surface Mechanical - Thermal Thermal expansion Repeated daily heating and cooling of rock Different minerals expand and
contract at different rates causing the rock to split Mechanical - Biotic Biotic means life Weathering caused by living organisms
Plant roots, digging animals, microscopic plants and animals, algae and fungi. Mechanical Weathering What is Chemical Weathering? Breakdown of rock into smaller pieces
because of change in the chemical composition of its minerals. Chemical reactions break down the bonds holding the rocks together, causing them to fall apart. Chemical weathering occurs in all types of rock but smaller rocks are more susceptible
because they have a greater amount of surface area. Chemical Weathering Types of chemical weathering
Oxidation (oxygen) Hydrolysis (water) Carbonation (carbon dioxide)
Biotic (living organisms) Acid rain Chemical - Oxidation Oxidation - oxygen combines with other elements in rocks to form new types of rock.
Causes a rusting of the rock, often causes a color change in the rock Chemical - Hydrolysis Hydrolysis - water combines with the substances in rocks to form new types of rock
New substances are softer than the original rock types Chemical - Carbonation Carbonation Carbon dioxide is dissolved in water making carbonic acid, which eats away at the rock
Weak acid is formed when carbon dioxide in the air mixes with rain. This is the same acid found in soft drinks. Chemical - Biotic Organisms - living organisms can cause changes in the chemistry of rock
Plants lower the local pH to make it more acidic Bacteria act as catalysts in various geochemical processes Chemical Weathering
Weathering by Water Most important agent of chemical weathering It can dissolve rock and minerals in rock Weathering by Waves Waves weather the land: Mechanical weathering
Broken down into smaller pieces Chemical weathering Dissolved in water Weathering by Waves
Weathering by Wind Wind weathers the land by mechanical means Abrasion Very slow process
Weathering by Wind weathering The breaking down of rock into smaller pieces that remain next to each other. Weathering forms sediments mechanical weathering
chemical weathering Physical breaking of rock without any change in the chemical composition of the rock.
biotic force ice wedging exfoliation
thermal The breaking down of rock into smaller pieces because of chemical changes within the rock. biotic
oxidation hydrolysis carbonation
Erosion What Caused This? http://commons.wikimedia.org/wiki/ File:Water_erosion_below_Hay_Bluff_-_geograph.org.uk__1074175.jpg
http://commons.wikimedia.org/wiki/ File:Wind_erosion_Seminole_Canyon.JPG http://commons.wikimedia.org/wiki/ File:Baventian_Clay_Beds_-_geograph.org.uk__1776748.jpg Erosion
Movement of weathered rock and soil to a new location. gravity water glaciers waves wind
What Is Gravitational Erosion? downward movement of rock and sediments, mainly due to the force of gravity. Erosion by Gravity
Gravity can erode landscapes
Landslides Mudflow Slump Creep Erosion by Water Moving water is the strongest agent of
erosion that has shaped Earths land surface Erosion by water starts with rain. As the rain runs downhill, it carries soil rock and other material with it Erosion by Water
The rate depends on amount of rain, vegetation, type of soil, shape of land, and how people use the land As water moves fast, it picks up sediment As water slows down, it drops sediment
Water What Is Glacial Erosion? moves and carries rocks, grinding the rocks beneath the glacier Glaciers pluck and abrade to cause erosion
Erosion by Glaciers What Is Wave Erosion? Waves - relentless pounding of waves that erodes the weaker, softer rock Can take over 100 years to erode a rock to
sand Erosion by Waves When waves hit rocky coastlines, the impact can break off pieces of the rock The sand and sediment in the waves can also act like sandpaper and wear
away rock Waves What Is Wind Erosion? wind picks up surface material and moves it, weakest agent of erosion
responsible for creating great deserts like the Sahara Desert and Gobi Wind erosion Movement of sediments from one
place to another. wind glaciers water
gravity waves Deposition Deposition
laying down (dropping) of sediment carried by wind, water, or ice Deposition by Water Water is the strongest agent of deposition.
Rivers deposit soil and sediment on their flood plains and deltas Good farmland is usually based on land where sediment was deposited by water Deposition by Water
Water Deposition Deposition by Glaciers When a glacier melts, it deposits the sediment it eroded from the land This deposition can create new
landforms and deposit sediment in new areas Till material deposited on the lands surface Moraine ridge at the edge of a glacier
Glacier Deposition Deposition by Waves Waves shape coastlines by depositing sand on the beach The type of sand is determined by the sediment on the ocean floor
White sand Black sand Deposition by Waves Deposition by Wind Wind is the weakest agent of
deposition When it drops the sediment it is carrying, it can form dunes or mounds Deposition by Wind deposition
Laying down of sediment that was carried in from another place. wind water
glacier waves Wind, water, and waves work together in the processes of deposition, weathering, and erosion
Whats the Difference? WEATHERING - think weather wearing rock down EROSION - think of a road and traveling DEPOSITION think of depositing money
in a bank
