Weathering and Soil Weathering and Soil FormationFormation

Chapter 10Chapter 10

Weathering Weathering

Weathering is simply the breakdown of Weathering is simply the breakdown of rock into smaller and smaller pieces called rock into smaller and smaller pieces called sediment.sediment.

Rocks on the Earth’s surface are Rocks on the Earth’s surface are undergoing weathering all the time, either undergoing weathering all the time, either by mechanical means or by chemical by mechanical means or by chemical means.means.

Mechanical WeatheringMechanical Weathering

Mechanical weathering is simply the Mechanical weathering is simply the breakdown of rock into smaller pieces by breakdown of rock into smaller pieces by physical means.physical means.

Agents or causes of mechanical Agents or causes of mechanical weathering include:weathering include: IceIce - gravity- gravity WindWind - plants- plants WaterWater - animals- animals

Agents of Mechanical WeatheringAgents of Mechanical Weathering

Explain how each of the following Causes Explain how each of the following Causes mechanical Weathering:mechanical Weathering: Ice (Define Ice Wedging)Ice (Define Ice Wedging) Wind, Water, and Gravity (Define Abrasion)Wind, Water, and Gravity (Define Abrasion) PlantsPlants AnimalsAnimals

WeatheringChapter 10 Mechanical Weathering

Ice Wedging

Ice Wedging occurs when water seeps into cracks of rocks and constantly freezes and thaws expanding the rock and eventually breaking it apart

https://www.youtube.com/watch?v=_XnCTcjNpuc

http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80127.htm

Mechanical WeatheringAbrasion

Abrasion: Abrasion is the grinding and wearing away of rock surfaces through the mechanical action of other rock or sand particles.

http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80130.htm

https://www.youtube.com/www.youtube.com/watch?v=JA4BdLkiRtgwatch?v=JA4BdLkiRtg

Mechanical Weathering

Wind, Water, and Gravity: Wind, water, and gravity carry rocks, causing them to abrade against one another.

Mechanical Weathering(Biological Weathering)

Plants As a plant grows, the force of the expanding root becomes so strong that it can break a rock apart. (Biological Weathering)

Animals and Mechanical Weathering (Biological

Weathering)

Animals that burrow in the ground break up soil and loosen rocks to be exposed to further weathering (Biological Weathering)

Chemical WeatheringChemical Weathering

Chemical Weathering is the chemical Chemical Weathering is the chemical breakdown of rocks and minerals into new breakdown of rocks and minerals into new substances. substances.

The most common agents or causes of The most common agents or causes of chemical weathering are:chemical weathering are: WaterWater Weak AcidsWeak Acids AirAir SoilSoil

Agents of Chemical WeatheringAgents of Chemical Weathering

Explain how each of the following Causes Explain how each of the following Causes Chemical WeatheringChemical Weathering WaterWater Acid PrecipitationAcid Precipitation Acid in Ground WaterAcid in Ground Water Acids in Living ThingsAcids in Living Things Air (Define and explain the result of Oxidation)Air (Define and explain the result of Oxidation)

Chemical Weathering Water Even hard rock, such as granite, can be

broken down by water.

Chemical Weathering(Acid Precipitation)

Sometimes precipitation contains more acid than normal. Sometimes precipitation contains more acid than normal. Rain, sleet, or snow that contains more acid than normal is Rain, sleet, or snow that contains more acid than normal is called called acid precipitationacid precipitation..

Acid precipitation forms Acid precipitation forms when small amounts of certainwhen small amounts of certaingases mix with water in the atmosphere. gases mix with water in the atmosphere.

The gases come from natural sources, such as The gases come from natural sources, such as active active volcanoesvolcanoes..They are also produced when people They are also produced when people burn fossil fuels,burn fossil fuels,such as coal and oil.such as coal and oil.

Acid Precipitation The high level of acidity in acid precipitation can cause very rapid weathering of rock.

Chemical Weathering(Biological Weathering)

Acids in Living Things Some living things, such as lichens, produce acids that can slowly break down rocks.

https://www.youtube.com/watch?v=zv2JNaqnYxU&index=2&list=PLEE924CE51E2604AD

Lichens, which consist of fungi and algae living together, contribute to chemical weathering.

Chemical Weathering

Acids in Groundwater When acidic groundwater comes into contact with limestone, the limestone is dissolved and forms karst features.

When the groundwater touches some kindsWhen the groundwater touches some kinds of rock, a chemical reaction happens. The chemical reactionof rock, a chemical reaction happens. The chemical reaction dissolves the rock. Over a long period of time, hugedissolves the rock. Over a long period of time, huge caves can form where rock has been dissolved.caves can form where rock has been dissolved.

Acid in groundwater has weathered limestone to form Rusty’s Cave in Dade

County, Georgia.

Chapter 10Oxidation

Air Oxygen in the air causes oxidation. Oxidation is the chemical reaction in which an element, such as iron, combines with oxygen to form an oxide.

http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80128.htm

https://www.youtube.com/watch?v=6VnVRHIV6j4

Section 10.2 (Rates of Section 10.2 (Rates of Weathering)Weathering)

Differential WeatheringSection 2

What Is Differential Weathering? Differential weathering is a process by which softer, less weather resistant rock wear away and leave harder, more weather resistant rock. The image below is an example of differential weathering.

The Shape of Rocks Surface Area The more

surface area of a rock that is exposed to weathering, the faster the rock will be worn down.

Increasing the Rate of Weathering If a large rock is broken down into smaller fragments, weathering of the rock happens much more quickly.

Surface Area and VolumeSurface Area and Volume

Weathering and Climate What Is Climate? Climate is the average weather

condition in an area over a long period of time.

Temperature and Water The rate of chemical weathering happens faster in warm, humid climates. Water also increases the rate of mechanical weathering.

The Source of SoilSection 3

What Is Soil? Soil is a loose mixture of small mineral fragments, organic material, water, and air that can support the growth of vegetation.

Residual and Transported Soil: Soil that remains above its parent rock is called residual soil. Soil that is blown or washed away from its parent rock is called transported soil.

SoilSoil

Ch. 11Ch. 11

LoamLoam

Loam, a type of very Loam, a type of very fertile soil is made fertile soil is made up of air, water and up of air, water and organic materials as organic materials as well as minerals well as minerals from weathered from weathered rock.rock.

Rich fertile soil that Rich fertile soil that is made up of about is made up of about equal parts of clay equal parts of clay sand and silt. sand and silt.

Soil Properties

• Soil Texture and Soil Structure Soil texture is the soil quality that is based on the proportions of soil particles. Soil structure is the arrangement of soil particles.

Transported soil may be moved long distances from its parent rock by rivers, such as this one.

Soil TextureSoil Texture

Soil Properties 2 Soil Fertility A soil’s

ability to hold nutrients and to supply nutrients to a plant is described as soil fertility.

Soil Horizons Because of the way soil forms, soil often ends up in a series of layers called horizons.

Soil pH Soils can be acidic or basic. The pH scale is used to measure how acidic or basic a soil is.

Soil LayersSoil Layers

The Importance of SoilSection 4

Nutrients Soil provides minerals and other nutrients for plants. All animals get their energy from plants.

Housing Soil provides a place for animals to live.

Water Storage Without soil to hold water, plants would not get the moisture or the nutrients they need.

Soil Damage and Loss Overuse Overused soil can lose its nutrients and become

infertile.

Soil Erosion When soil is left unprotected, it can be exposed to erosion. Erosion is the process by which wind, water, or gravity transport soil and sediment from one location to another.

Providence Canyon, Georgia, shows the effects of cutting forests for farm land.

Providence CanyonProvidence CanyonProvidence Canyon is near Lumpkin, Georgia.  It has beautiful gullies formed by erosion 150 years ago. This park is part of Georgia's East Gulf Coastal Plain region. People call it Georgia's "Little Grand Canyon."  There are 16 canyons altogether.  Some canyons are 1 mile long and 300 feet across.  An ancient ocean formed all the

canyons.

Georgia Red ClayGeorgia Red Clay

Georgia is famous for Georgia is famous for its red clay.its red clay.

This red color comes This red color comes from the high iron from the high iron content in the soil.content in the soil.

Think rust!Think rust!

Dust BowlDust Bowl In the 1800’s settlers in the In the 1800’s settlers in the

Great Plains turned the Great Plains turned the fertile, moisture laden sod fertile, moisture laden sod into farmland.into farmland.

In drought, this land dried In drought, this land dried up and blew away as dust.up and blew away as dust.

In the 1930’s, severe In the 1930’s, severe drought over several years drought over several years allowed this soil to be blown allowed this soil to be blown away in great, dark clouds.away in great, dark clouds.

Some of these dust storms Some of these dust storms reached New York City.reached New York City.

This lasted until 1938. This lasted until 1938. Many farmers in the “Dust Many farmers in the “Dust Bowl” had to abandon their Bowl” had to abandon their homes and move away.homes and move away.

Read Steinbeck’s “The Read Steinbeck’s “The Grapes of Wrath”Grapes of Wrath”

Soil ConservationSoil Conservation

A method to maintain the fertility of the soil by A method to maintain the fertility of the soil by protecting the soil from erosion and chemical protecting the soil from erosion and chemical decay.decay.

The Importance of Soil

Nutrients Soil provides minerals and other nutrients for plants. All animals get their energy from plants.

Housing Soil provides a place for animals to live.

Water Storage Without soil to hold water, plants would not get the moisture or the nutrients they need.

Why is soil Important?Why is soil Important?

Soil is one of Earth’s most valuable resources Soil is one of Earth’s most valuable resources because every thing that lives on land depends because every thing that lives on land depends directly or indirectly on soil.directly or indirectly on soil.

Plants depend directly on the soil to live and Plants depend directly on the soil to live and grow. grow.

Animals depend on plants or on other animals Animals depend on plants or on other animals for food. for food.

Fertile soil is valuable because there is a limited Fertile soil is valuable because there is a limited supply. supply.

Soil Damage and Loss Overuse Overused soil can lose its nutrients and become

infertile.

Soil Erosion When soil is left unprotected, it can be exposed to erosion. Erosion is the process by which wind, water, or gravity transport soil and sediment from one location to another.

Providence Canyon, Georgia, shows the effects of cutting forests for farm land.

Soil Damage/ LossSoil Damage/ Loss

Soil damage can lead to soil loss.

Soil can be damaged from overuse by poor farming techniques or by overgrazing.

Overused soil can lose its nutrients and become infertile. Plants can’t grow in soil that is infertile. Without plants to hold and help cycle water, the area can become a desert..

Soil ErosionSoil Erosion

When soil is left unprotected, it can be exposed to erosion.

 Erosion is the process by which wind, water, or gravity transport soil and sediment from one location to another.

Roots from plants and trees are like anchors to the soil. Roots keep topsoil from being eroded. Therefore, plants and trees protect the soil.

What human activities affect soil What human activities affect soil erosion?erosion?

FarmingFarming Construction and developmentConstruction and development Mining Mining

What can be done to prevent What can be done to prevent soil erosion? soil erosion?

Contour PlowingContour Plowing Conservation PlowingConservation Plowing TerracingTerracing WindbreaksWindbreaks Crop RotationCrop Rotation

Contour Plowing and Terracing Contour Plowing In

contour plowing farmers plowed rows so that they run up and down hills. The rows of soil act as a series of dams to prevent water from eroding topsoil away.

Terracing If hills are steep, farmers can use terracing. Terracing changes one steep field into a series of smaller, flatter fields. Prevents erosion from heavy rains on steep hills

No Till Farming and Cover Crop

No-till farming, which is the practice of leaving old stalks, provides cover from rain. The cover reduces water runoff and slows soil erosion.

Cover Crops are crops that are planted between harvests to replace certain nutrients and prevent erosion. Cover crops prevent erosion by providing cover from wind and rain.

Crop Rotation and Windbreaks

Crop Rotation Farmers can rotate crops that use different nutrients so that nutrients in the soil have time to become replenished.

Windbreaks Rows of Rows of trees are planted along the trees are planted along the edges of fields. edges of fields. Block the Block the wind and also trap eroding wind and also trap eroding soil.soil.