Chapter Introduction Lesson 1 Weathering Lesson 2 Soil Chapter Wrap-Up Chapter Menu

What natural processes break down rocks and begin soil formation? Chapter Introduction

What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements. Chapter Introduction

Do you agree or disagree? 1. Weathering is the same as erosion. 2. Humans are the main cause of weathering. 3. Plants can break rocks into smaller pieces. Chapter Introduction

Do you agree or disagree? 4. Air and water are present in soil. 5. Soil that is 1,000 years old is young soil. 6. Soil is the same in all locations. Chapter Introduction

Lesson 1 Reading Guide - KC Weathering How does weathering break down or change rock? How do mechanical processes break big rocks into smaller pieces? How do chemical processes change rocks? Lesson 1 Reading Guide - KC

Lesson 1 Reading Guide - Vocab Weathering weathering mechanical weathering chemical weathering oxidation Lesson 1 Reading Guide - Vocab

Weathering and Its Effects The mechanical and chemical processes that change objects on Earth’s surface over time are called weathering. Over thousands of years, weathering can break rock into smaller and smaller pieces, such as sand, silt, and clay. Lesson 1-1

Weathering and Its Effects (cont.) Science Use to change from the action of the environment Common Use the state of the atmosphere Lesson 1-1

Weathering and Its Effects (cont.) How does weathering break down or change rock? Lesson 1-1

Mechanical Weathering When physical processes naturally break rocks into smaller pieces, mechanical weathering occurs. The chemical makeup of a rock stays the same during mechanical weathering. Mechanical weathering can be caused by ice wedging, abrasion, plants, and animals. Lesson 1-2

Lesson 1-2

Mechanical Weathering (cont.) An example of mechanical weathering is when the intense heat of a forest fire causes nearby rocks to expand and crack. When something is broken into smaller pieces, it has a greater surface area. Surface area is the amount of space on the outside of an object. Lesson 1-2

Mechanical Weathering (cont.) What are five ways mechanical weathering breaks large rocks into smaller pieces? Lesson 1-2

Chemical Weathering Chemical weathering changes the materials that are part of a rock into new materials. These granite obelisks show how chemical weathering can affect some rock. Dr. Marli Miller/Getty Images Lesson 1-3

Chemical Weathering (cont.) Water is important in chemical weathering because most substances dissolve in water. The process of dissolving breaks up the minerals in the rock into small pieces. The small pieces mix with water to form a solution and are washed away from the rock. Acids are also agents of chemical weathering and cause more chemical weathering than pure water does. Lesson 1-3

Chemical Weathering (cont.) Oxidation combines the element oxygen with other elements or molecules. The product of oxidation is called an oxide. When rocks that contain iron oxidize, a layer of iron oxide forms on the outside surface. Lesson 1-3

Chemical Weathering (cont.) How does chemical weathering change rock? Lesson 1-3

What affects weathering rates? The environment helps determine the rate of weathering. Mechanical weathering occurs fastest in locations that have a lot of temperature changes. Chemical weathering is fastest in warm, wet places. The type of rock being weathered also affects the rate of weathering and determines what kinds of products result. Lesson 1-4

Weathering is the mechanical and chemical processes that change things over time. Mechanical weathering does not change the identity of the materials that make up rocks. It breaks up rocks into smaller pieces. Lesson 1 - VS

Chemical weathering is the process that changes the minerals that are part of every rock into new materials. Oxidation and reaction with an acid are both examples of chemical weathering. Dr. Marli Miller/Getty Images Lesson 1 - VS

The minerals that make up rock change during which of these? A. mechanical weathering B. chemical weathering C. ice wedging D. abrasion Lesson 1 – LR1

Which of these are agents of chemical weathering? A. water B. acids C. animals D. A and B Lesson 1 – LR2

B. mechanical weathering C. surface area D. abrasion Which term refers to the amount of space exposed on the outside of an object? A. oxidation B. mechanical weathering C. surface area D. abrasion Lesson 1 – LR3

1. Weathering is the same as erosion. Do you agree or disagree? 1. Weathering is the same as erosion. 2. Humans are the main cause of weathering. 3. Plants can break rocks into smaller pieces. Lesson 1 - Now

Lesson 2 Reading Guide - KC Soil How is soil created? What are soil horizons? Which soil properties can be observed and measured? How are soils and soil conditions related to life? Lesson 2 Reading Guide - KC

Lesson 2 Reading Guide - Vocab Soil soil organic matter pore decomposition parent material climate topography biota horizon Lesson 2 Reading Guide - Vocab

What is soil? Soil is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air. Organic matter is the remains of something that was once alive. Decomposition is the process of changing once-living material into dark-colored organic matter. Lesson 2-1

What is soil? (cont.) Soil contains gases that fill the soil pores–the small holes and spaces in soil. pore from Greek poros, means “passage, way” Lesson 2-1

What is soil? (cont.) The sizes of pores change with differences in particle size. Lesson 2-1

Formation of Soil Inorganic matter in soil is formed by the mechanical and chemical weathering of rocks into fragments. The term inorganic describes materials that have never been alive. Lesson 2-1

Formation of Soil (cont.) Parent material is the starting material of soil. Parent material is made of the rock or sediment that weathers to form the soil. Lesson 2-2

Formation of Soil (cont.) What is the role of parent material in creating soil? Lesson 2-2

Formation of Soil (cont.) The average weather of an area is its climate. If the parent material is in a warm, wet climate, soil formation can be rapid. Topography is the shape and steepness of the landscape. Lesson 2-2

Formation of Soil (cont.) The topography of an area determines what happens to water that reaches the soil surface. Water running downhill can carry soil with it, leaving some slopes bare of soil. Lesson 2-2

Formation of Soil (cont.) Biota is all of the organisms that live in a region. Biota in the soil help speed up the process of soil formation in various ways. Organisms can be involved in decomposition of organic matter or form passages in soil for water to move through. Lesson 2-2

Rock and soil are affected by organism activity. Lesson 2-2

Formation of Soil (cont.) How does biota aid in soil formation? Lesson 2-2

Mature soils develop layers as new soil forms on top of older soil. Lesson 2-2

Horizons As time passes, weathering is constantly acting on rock and sediment, making soil formation a constant, but slow, process. Horizons are layers of soil formed from the movement of the products of weathering. Lesson 2-2

Horizons (cont.) horizon from Latin horizontem, means “bounding circle” Lesson 2-3

Horizons (cont.) Each horizon has characteristics based on the type of materials it contains. The three horizons common to most soils are identified as A-horizon, B-horizon, and C-horizon. The top, organic layer is called the O-horizon and the unweathered, bedrock layer is the R-horizon. Lesson 2-3

Horizons (cont.) What are soil horizons? Lesson 2-3

Soil Properties and Uses Lesson 2-4

Soil Properties and Uses (cont.) Lesson 2-4

Soil Properties and Uses (cont.) Some properties of soil can be determined just by observation. The amount of sand, silt, and clay in a soil can be estimated by feeling the soil. Many soil properties can be measured more accurately in a laboratory. Lesson 2-4

Soil Properties and Uses (cont.) Laboratory measurements can determine exactly what is in each sample of soil. List soil properties that can be observed and measured. Lesson 2-4

Soil Properties and Uses (cont.) Plant growers can observe how well plants grow in the soil to get information about soil nutrients. How is soil related to life? Lesson 2-4

The type of soil formed depends partly on climate. Lesson 2-4

Soil Properties and Uses (cont.) Are soils the same everywhere? Lesson 2-5

The inorganic matter in soil is made up of weathered parent material The inorganic matter in soil is made up of weathered parent material. The organic matter in soil is made by the decomposition of things that once lived. Lesson 2 - VS

The five factors of soil formation are parent material, topography, climate, biota, and time. Soil contains horizons, which are layers formed from the movement of the products of weathering. Most soil contains A-, B-, and C-horizons. Lesson 2 - VS

D. mechanical weathering Which term refers to the process of changing once-living material into dark-colored organic matter? A. biota B. topography C. decomposition D. mechanical weathering Lesson 2 – LR1

Which of these refers to the starting material of soil? A. parent material B. bed rock C. biota D. horizons Lesson 2 – LR2

Which of these is the top, organic layer of soil? A. A-horizon B. B-horizon C. C-horizon D. O-horizon Lesson 2 – LR3

4. Air and water are present in soil. Do you agree or disagree? 4. Air and water are present in soil. 5. Soil that is 1,000 years old is a young soil. 6. Soil is the same in all locations. Lesson 2 - Now

Interactive Concept Map Chapter Review Standardized Test Practice Key Concept Summary Interactive Concept Map Chapter Review Standardized Test Practice Chapter Review Menu

Physical and chemical weathering are destructive forces that break down rocks, which begins the formation of soil. The BIG Idea

Lesson 1: Weathering Weathering acts mechanically and chemically to break down rocks. Through the action of Earth processes such as freezing and thawing, mechanical weathering breaks rocks into smaller pieces. Chemical weathering by agents such as water and acids change the materials in rocks into new materials. Dr. Marli Miller/Getty Images Key Concepts 1

Lesson 2: Soil Five factors–parent material, climate, topography, biota, and time–affect the formation of soil. Horizons are soil layers formed from the movement of the various products of weathering. Soil can be characterized by properties such as the amount of organic matter and inorganic matter. Plants depend on certain characteristics of soil, such as organic matter and amount of weathering. Key Concepts 2

B. mechanical weathering C. oxidation D. ice wedging Which term refers to what happens when physical processes naturally break rocks into smaller pieces? A. chemical weathering B. mechanical weathering C. oxidation D. ice wedging Chapter Review – MC1

What is the product of oxidation? A. oxygen B. an oxide C. acid D. iron Chapter Review – MC2

Where does chemical weathering occur fastest? A. cool, dry places B. places with a lot of temperature changes C. warm, wet places D. none of these Chapter Review – MC3

Which term refers to the shape and steepness of a landscape? A. biota B. pores C. horizons D. topography Chapter Review – MC4

Which of these refers to all of the organisms that live in a region? A. organic matter B. soil C. biota D. horizons Chapter Review – MC5

A. mechanical weathering B. abrasion C. chemical weathering Which term refers to changes in the materials that are part of a rock into new materials? A. mechanical weathering B. abrasion C. chemical weathering D. ice wedging Chapter Review – STP1

Which of these can cause mechanical weathering? A. ice wedging B. abrasion C. plants D. all of the above Chapter Review – STP2

A. mechanical weathering B. oxidation C. chemical weathering Which of these occurs fastest in locations that have a lot of temperature changes? A. mechanical weathering B. oxidation C. chemical weathering D. none of these Chapter Review – STP3

Which term refers to the small holes and spaces in soil? A. biota B. pores C. horizons D. silt Chapter Review – STP4

A. The surface area of the broken pieces is larger. Why will weathering occur more quickly to a rock that has been broken into several pieces? A. The surface area of the broken pieces is larger. B. The surface area of the broken pieces is smaller. C. The total weight of the rock decreases when it is broken. D. The total weight of the rock increases when it is broken. Chapter Review – STP5