Weathering and Weathering and ErosionErosion

Properties of Properties of Earth's Water and Earth's Water and

AtmosphereAtmosphereSOL 6.5SOL 6.5

Weathering= the process that Weathering= the process that breaks breaks downdown rock and other substances at rock and other substances at Earth's surface. Earth's surface. AgentsAgents of weathering= heat, cold, of weathering= heat, cold,

waterwater, ice, as well as , ice, as well as oxygenoxygen and and carbon dioxide in the atmosphere. carbon dioxide in the atmosphere.

Examples of Weathering:Examples of Weathering: Mountains Mountains wearing awaywearing away over time over time Bicycles rustingBicycles rusting Paint peelingPaint peeling SidewalksSidewalks cracking cracking Formation of Formation of potholespotholes in road in road

The forces of weathering The forces of weathering breakbreak rocks rocks into smaller and smaller pieces. Then into smaller and smaller pieces. Then the forces of erosion the forces of erosion carrycarry those those pieces away. pieces away.

Erosion= the Erosion= the movementmovement of rock of rock particles by particles by windwind, water, ice, or , water, ice, or gravitygravity. .

Weathering and erosion Weathering and erosion work work togethertogether continuously to wear down continuously to wear down and carry away the rocks at Earth's and carry away the rocks at Earth's surface. surface.

There are 2 types of weathering and they There are 2 types of weathering and they work together:work together:

MechanicalMechanical weathering= the type of weathering= the type of weathering where rock is weathering where rock is physicallyphysically broken broken down into smaller pieces.down into smaller pieces. How it happens: by freezing and thawing (How it happens: by freezing and thawing (ice ice

wedgingwedging), release of pressure, growth of plants, ), release of pressure, growth of plants, actions of actions of animals,animals, and and abrasionabrasion (grinding away (grinding away of rock by water, ice, wind or gravity). of rock by water, ice, wind or gravity).

Produces smaller pieces of the Produces smaller pieces of the samesame exact exact material.material.

This type of weathering This type of weathering works slowlyworks slowly, but over , but over time it will eventually wear away whole time it will eventually wear away whole mountains.mountains.

Ice WedgingIce Wedging

ChemicalChemical Weathering=process that breaks Weathering=process that breaks down rock through down rock through chemicalchemical changes. changes. How it happens: by How it happens: by waterwater, oxygen, carbon , oxygen, carbon

dioxide, living organisms and dioxide, living organisms and acid rainacid rain. . Produces rock products that have a Produces rock products that have a differentdifferent

makeup from the rock they came from. makeup from the rock they came from. Example: chemical weathering of granite changes the Example: chemical weathering of granite changes the

minerals that make up the granite into something else.minerals that make up the granite into something else. Chemical weathering Chemical weathering creates holescreates holes and soft spots and soft spots

in rock so that it breaks apart more easily. in rock so that it breaks apart more easily.

CheckpointCheckpoint How do you think physical and How do you think physical and

chemical weathering work together chemical weathering work together to wear down rock?to wear down rock?

The most important factors that The most important factors that determine the determine the raterate at which at which weathering occurs are the weathering occurs are the type of type of rock and climaterock and climate. . Whether the material easily dissolves in Whether the material easily dissolves in

water or not.water or not. Whether the material is Whether the material is permeablepermeable.. Wet, hotWet, hot climates vs. dry, cold climates. climates vs. dry, cold climates.

WaterWater is the most important agent of is the most important agent of chemical weathering because it chemical weathering because it causes the most chemical weathering causes the most chemical weathering to happen. to happen. Water weathers rock by Water weathers rock by dissolvingdissolving it. it.

When a rock or other substance When a rock or other substance dissolves in water, it mixes uniformly dissolves in water, it mixes uniformly throughout the water to make a throughout the water to make a solutionsolution. .

Speaking of Water...Speaking of Water... The Earth’s surface is made up of ¾ The Earth’s surface is made up of ¾

waterwater.. Only 3% of the Earth's water is Only 3% of the Earth's water is

freshwater; the other freshwater; the other 97%97% is is salt water.salt water. Most of this freshwater is found near the Most of this freshwater is found near the

North and South PolesNorth and South Poles in glaciers, in glaciers, leaving only leaving only 1%1% of it usable for humans. of it usable for humans. This makes freshwater a This makes freshwater a limited limited resourceresource which we need to conserve. which we need to conserve.

We need water!We need water! Water is important to Water is important to human lifehuman life as as

well as other living organisms.well as other living organisms. Our body is made up of Our body is made up of more than 50%more than 50%

water.water. Water is used to Water is used to grow foodgrow food and is and is

important for important for public healthpublic health. .

GroundwaterGroundwater A lot of water is found underground in an A lot of water is found underground in an

aquifer. An aquifer. An aquiferaquifer is any is any undergroundunderground layer of rock or sediment that holds water. layer of rock or sediment that holds water.

Some underground water eventually makes Some underground water eventually makes it to the surface in it to the surface in springssprings, streams and , streams and ponds.ponds.

Humans can also help bring water Humans can also help bring water underground to the surface through the underground to the surface through the use of use of wellswells. About . About halfhalf the people in the the people in the United States get their water this way. United States get their water this way.

Other ways to get water...Other ways to get water... An An aqueductaqueduct carries water from one carries water from one

place to another. place to another.

This aqueduct, the Pont du Gard in France, This aqueduct, the Pont du Gard in France, was built by the Romans more than 2,000 was built by the Romans more than 2,000 years ago. years ago.

Since we have a Since we have a limitedlimited amount of amount of freshwater on Earth and an abundant freshwater on Earth and an abundant amount of salt water, we use the amount of salt water, we use the process of process of desalinationdesalination. .

The process of desalination causes The process of desalination causes the the water to evaporatewater to evaporate from the from the saltwater creating usable freshwater. saltwater creating usable freshwater. This method creates a This method creates a large amountlarge amount of freshwater. of freshwater.

Remember Water's Remember Water's Specific Heat...?Specific Heat...?

Water's specific heat allows large Water's specific heat allows large bodies of water to bodies of water to slowlyslowly absorb and absorb and release heat, making it release heat, making it stay warmer stay warmer longerlonger than land. than land.

This allows the This allows the climateclimate near areas of near areas of large bodies of water (oceans) to be large bodies of water (oceans) to be mildermilder in both the summer and in both the summer and winter. winter.

Atmosphere of EarthAtmosphere of Earth Earth's atmosphere is made up of Earth's atmosphere is made up of

mostly mostly NitrogenNitrogen. . 78% nitrogen78% nitrogen 21% 21% oxygenoxygen 1% other gases1% other gases

Soil Soil forms as rock (exposed forms as rock (exposed bedrockbedrock) ) is broken down by weathering and is broken down by weathering and mixes with other materials on the mixes with other materials on the surface. surface. It is a It is a mixturemixture of rock particles, of rock particles,

minerals, decayed organic material minerals, decayed organic material (humus), air, and water. (humus), air, and water.

A A soil horizonsoil horizon, is a , is a layerlayer of soil that of soil that differs in color and texture from the differs in color and texture from the layers above or below it. layers above or below it.

Topsoil= crumbly and dark brown. Composed of humus, clay and other minerals.

Subsoil=composed of clay and other particles.

In the United States alone, In the United States alone, differences in climate and local differences in climate and local bedrock have led to the formation of bedrock have led to the formation of thousands of thousands of different types of soildifferent types of soil. . The different types of soil are The different types of soil are classifiedclassified

by:by: climateclimate of the region it is found of the region it is found the different the different plantsplants living in that region living in that region its its compositioncomposition (rocky, sandy, or full of (rocky, sandy, or full of

clay). clay).

Soil Types FoldableSoil Types Foldable Tundra SoilsTundra Soils Northern forest soilsNorthern forest soils Prairie SoilsPrairie Soils Mountain SoilsMountain Soils Southern Forest SoilsSouthern Forest Soils Desert SoilsDesert Soils Tropical SoilsTropical Soils

Tundra SoilsTundra Soils Forms where it is cold year roundForms where it is cold year round Thin soil with little humus.Thin soil with little humus.

Land is a precious resource. Land is a precious resource.

““They don't make it anymore.” --Mark They don't make it anymore.” --Mark TwainTwain

LandLand makes up only a makes up only a ¼ ¼ of the Earth's of the Earth's surface.surface.

All the people on Earth must All the people on Earth must shareshare this this limited amount of land to produce food, limited amount of land to produce food, build shelter, and obtain other resources. build shelter, and obtain other resources.

Northern Forest SoilNorthern Forest Soil Form in cool, wet climatesForm in cool, wet climates Can be thick and fertile or thin with Can be thick and fertile or thin with

little humus.little humus.

Prairie SoilsPrairie Soils Form in cool, dry climates of Form in cool, dry climates of

grasslandsgrasslands Topsoil is thick and rich in humusTopsoil is thick and rich in humus

Mountain SoilsMountain Soils Topsoil often thin because cold Topsoil often thin because cold

temperatures slow chemical temperatures slow chemical weathering and erosion causes soil weathering and erosion causes soil loss. loss.

Southern Forest SoilsSouthern Forest Soils Form in warm, wet climatesForm in warm, wet climates May be low in humusMay be low in humus

Tropical SoilsTropical Soils Form in wet, tropical climatesForm in wet, tropical climates Often low in humus and mineralsOften low in humus and minerals

Three uses that Three uses that changechange the land are the land are agriculture,agriculture, development, and mining. development, and mining.

Soil is one of the Earth's most valuable Soil is one of the Earth's most valuable resources because everything that lives resources because everything that lives on land depends directly or indirectly on land depends directly or indirectly on soil and there is a on soil and there is a limited supply of limited supply of fertile soil.fertile soil. less than 1/8 of soil on Earth is suitable for less than 1/8 of soil on Earth is suitable for

farmingfarming Soil can be lost or damaged.Soil can be lost or damaged.

Ways soil can be lost/damaged:Ways soil can be lost/damaged: Soil can be exhausted or Soil can be exhausted or lose its fertilitylose its fertility

by over farming.by over farming. Soil can be Soil can be pollutedpolluted by mining or by mining or

chemical spills.chemical spills. It can be lost to It can be lost to erosionerosion by water and by water and

wind.wind. DesertificationDesertification can happen in places can happen in places

with little rainfall (Plants die which with little rainfall (Plants die which causes wind to carry soil away), or in causes wind to carry soil away), or in places where overgrazing or clear cutting places where overgrazing or clear cutting has occured. has occured.

Example: the “Dust Bowl”Example: the “Dust Bowl”

Soil Conservation is the Soil Conservation is the managementmanagement of of soil to soil to preventprevent its destruction. its destruction. Contour plowingContour plowing= practice of plowing fields = practice of plowing fields

along the curvesalong the curves of a slope which helps to of a slope which helps to slow the runoff of excess rainfall and slow the runoff of excess rainfall and prevents the washing away of soil. prevents the washing away of soil.

Conservation plowingConservation plowing= disturbs the soil = disturbs the soil and its plant cover as little as possible. and its plant cover as little as possible. Dead Dead weedsweeds and stalks of the previous year's crop and stalks of the previous year's crop are left in place. are left in place.

Crop rotationCrop rotation= a method that helps = a method that helps preserve the soil's fertility. A farmer plants preserve the soil's fertility. A farmer plants different cropsdifferent crops in a field each year. in a field each year. Sometimes the fields are left Sometimes the fields are left fallowfallow or or unplanted. unplanted.

Windbreaks and Windbreaks and TerracingTerracing

Land reclamationLand reclamation= the process of = the process of restoring an area of land to a more restoring an area of land to a more natural, productive state. natural, productive state. Restoring lands for agricultureRestoring lands for agriculture Restore habitats for wildlifeRestore habitats for wildlife

It is It is harder to restoreharder to restore damaged land damaged land and soil than it is to protect them in and soil than it is to protect them in the first place. the first place.