Deposition, Weathering, and Erosion Weathering
What Caused This? http://en.wikipedia.org/wiki/File:KharazaArch.jpg http://commons.wikimedia.org/wiki/File:Toad_Rock_-_geograph.org.uk_-_76 7454.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 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 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
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
