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Transcript
This PowerPoint explains and reports important concepts students should learn and master in an Earth Science unit. The ideas presented should be understood by upper elementary and middle school student according to most state science standards as well as Next Generation Science Standards (NGSS). The concepts covered in this PowerPoint, as well as related activities and materials, are appropriate for upper elementary and middle school science classrooms. Concepts are differentiated by a colored shape code: Slides with a green circle deal with basic key ideas and understandings meant for upper elementary (grade 3-5) students. These concepts can or should be reviewed with intermediate/middle school (grade 6-8) students. Slides with a blue square deal with intermediate key ideas and understandings meant for middle school students. These concepts may be appropriate for high-achieving upper elementary students. According to NGSS, some of the “traditionally intermediate” level concepts are now recognized as upper elementary concepts. Slides with a black diamond cover advanced concepts. Some of these concepts may be appropriate for your intermediate students. Sometimes it helps students better understand the how and why of intermediate concepts if they are introduced to advanced concepts. This PowerPoint is meant to help students gain a first-order learning of Earth Science concepts. Students should be able to remember and understand the information presented. Additional activities available for purchase at my store will help students apply, analyze, create and synthesize knowledge important to a complete unit covering these concepts. 1 © Stephanie Elkowitz • • • • • • Soil Living & Nonliving Parts of Soil Formation of Soil Soil Textures Types of Soil Layers of Soil 2 © Stephanie Elkowitz • Soil or “dirt” covers the ground and is like the skin of Earth. • Soil covers all parts of Earth’s surface, including the “ground” of oceans, lakes and other bodies of water. Soil, Rocks & Minerals What is soil? 3 © Stephanie Elkowitz • Soil is a mixture of minerals, water, air and organic matter that formed from decomposed remains of plants and animals and waste produced by living things. • Soil also includes living things such as microorganisms, fungi and insects. Soil, Rocks & Minerals 4 © Stephanie Elkowitz • Soil is important because: – Plants extract water and nutrients from soil and use soil to anchor themselves. – Organisms such as bacteria, fungi and animals live in soil. – Soil helps cycle nutrients and substances, such as carbon and nitrogen, in the environment. – Water precipitates to the ground and flows along Earth’s surface. Water seeps into the ground to form groundwater. Soil filters and cleans the water. Soil, Rocks & Minerals 5 © Stephanie Elkowitz • When studying soil, we often consider the living and nonliving parts of soil. • The living parts of soil include organism that inhabit soil. • The nonliving parts of soil include the dead and nonliving substances that make up soil. These substances make up the material that we call dirt. Soil, Rocks & Minerals 6 © Stephanie Elkowitz • There are 5 major nonliving components of soil: – Sediments: small particles of broken down rock. – Minerals: important elements needed by living things in the soil, make up rocks, determine the fertility of soil – Nutrients: substances in soil that are used by living things to survive; the most important nutrients are nitrogen, phosphorus and potassium – Water: Water is found in between the particles of soil – Organic Matter: made from dead and decaying organisms Soil, Rocks & Minerals 7 © Stephanie Elkowitz • Many different living things live in soil or depend on soil: – Plants: establish their roots in soil to extract nutrients, water and other substances to help them grow – Bacteria: help decompose dead organisms and they help “prepare” nutrients, such as nitrogen, in the soil. Bacteria are plentiful in soil 1 teaspoon of soil can have up to 1 billion bacteria! – Animals: some animals, such as snakes and groundhogs burrow in soil, insects (ex. worms) in soil help decompose dead organisms – Fungi: important decomposers that break down dead organisms Soil, Rocks & Minerals 8 © Stephanie Elkowitz • Soil can take a long time to form. In fact, soil can take up to 1,000 years to form! There are 4 factors that influence how fast soil forms: 1. Organisms 2. Topography 3. Climate 4. Parent Material Soil, Rocks & Minerals 9 © Stephanie Elkowitz Factor #1: Organisms • Living things known as decomposers help break down dead organisms into organic matter. Organic matter is an important part of soil. • The kind and amount of decomposers in the soil can affect how fast organic matter forms. Soil, Rocks & Minerals 10 © Stephanie Elkowitz Factor #2: Topography • Elevation and slope make up the shape of the land. We call the shape of land topography. • Topography affects how fast soil forms. Water travels faster down steeper slopes. This causes faster soil formation along steep slopes. • Elevation and slope are also important to the type of soil that forms. Soil, Rocks & Minerals 11 © Stephanie Elkowitz Factor #3: Climate • Climatic factors, such as precipitation and temperature, affect how fast soil forms. These factors cause weathering. • Weathering is breaking down of rock. Weathering is important to soil formation. • Increased precipitation and warmer temperature causes faster weathering, which leads to faster soil formation. Soil, Rocks & Minerals 12 © Stephanie Elkowitz Factor #4: Parent Material • Parent material is solid rock and minerals found within Earth. • Over time, parent material breaks down to form soil. Some rocks and/or minerals break down faster than others. • Softer rock breaks down faster than harder rock. Soil, Rocks & Minerals 13 © Stephanie Elkowitz • In order for soil to form, there must first be parent material. Parent material is solid rock and minerals. • Parent material is often bedrock. Bedrock is hard, solid rock that covers Earth. This rock is formed from different natural processes. It can become exposed when overlying soil or rock erodes. Soil, Rocks & Minerals 14 © Stephanie Elkowitz • Over time, parent material is weathered or broken down into small particles. • The most influential weathering factors are wind, water and plants. Soil, Rocks & Minerals 15 © Stephanie Elkowitz • Eventually parent material is completely broken down into small particles. Water and gases mix with the rock and mineral particles. • Plants begin to grow in the material, organisms move into the material and larger organisms roam the surface of the material. • Organisms die and decompose into organic matter, which is incorporated into the material. Over time, the material transforms into soil. Soil, Rocks & Minerals 16 © Stephanie Elkowitz • There are several characteristics of soil. These characteristics include texture, density, color, consistency and porosity. • The most important characteristic of soil is texture. • Texture is a measure of what the soil feels like. Texture depends on the size of the particles within the soil. • Texture determines other characteristics of soil. Soil, Rocks & Minerals 17 © Stephanie Elkowitz • There are three soil textures: 1. Sand 2. Silt 3. Clay Soil, Rocks & Minerals 18 © Stephanie Elkowitz • Sand is made of large or coarse particles with diameters ranging from 0.05 to 2.00 millimeters. • Because sand is made of large particles, it feels gritty or rough. • It allows water and air to pass through easily. However, because it is porous, it does not hold nutrients or water well. Soil, Rocks & Minerals 19 © Stephanie Elkowitz • Silt is made of medium-sized particles with a diameter of 0.002 to 0.05 millimeters. • Because silt is made of smaller particles, it is not as rough as sand. When dry, it feels like smooth powder. When wet, it feels slippery. • Because its particles are smaller, it allows some drainage and air to pass through but holds onto nutrients. It can be easily packed down, which allows less water and air to pass through. Soil, Rocks & Minerals 20 © Stephanie Elkowitz • Clay is made of tiny or fine particles with a diameter less than 0.002 millimeters. • When dry, clay feel smooth and hard. When wet, it feels sticky. • Because its particles are fine, it holds onto water and nutrients very well and does not allow air to pass through easily. When wet, clay gets “heavy” from the water and then becomes very hard when dry. Soil, Rocks & Minerals 21 © Stephanie Elkowitz • The three soil textures form mixtures to make up different types of soil. Each type of soil has a different fraction or proportion of sand, silt and/or clay. • There are many different types of soil but we often focus on the three types below: 1. Sandy Soil 2. Clay Soil 3. Loamy Soil Soil, Rocks & Minerals 22 © Stephanie Elkowitz • Sandy soil is mostly (but not entirely) made of sand. Because sandy soil is mostly sand, it has properties very similar to sand, the soil texture. – Sandy soil is dry and gritty. The particles are large and there are spaces between the particles - they cannot hold water or nutrients. – Water drains quickly through sandy soil and so it’s usually dry. For this reason, sandy soil is not good for plants. Plants cannot extract enough water and nutrients in order to survive. • Sandy soil is common at beaches. Soil, Rocks & Minerals 23 © Stephanie Elkowitz • Clay soil is mostly (but not entirely) made of clay. Because clay soil is mostly clay, its properties are most like clay, the soil texture. – Clay soil is made of tiny particles that tend to settle together. This makes it hard for water and air to pass through. It also means clay soil holds onto nutrients tightly. – Clay soil poor soil for plants. Plants cannot extract water or nutrients from clay soil because the soil holds onto these substances so tightly. • Clay soil is found everywhere. Soil, Rocks & Minerals 24 © Stephanie Elkowitz • Loamy soil is made of almost equal parts sand, clay and silt. For this reason, it has characteristics of all three types of soil textures. • Loamy soil is considered to be the ideal soil type. It contains a balance of all three soil textures – plus organic matter. – It holds onto water and nutrients and drains water well. Air moves freely through loamy soil. – Loamy soil is the best for plants because of these characteristics. This soil is just right for plants. Soil, Rocks & Minerals 25 © Stephanie Elkowitz • Loamy soil makes up fertile lands. These lands are ideal for farming and other agricultural uses. Soil, Rocks & Minerals 26 © Stephanie Elkowitz • Most people think soil is just the “dirt” that covers the very top of the ground. In fact, soil is much more than just this material. • Soil is actually made of layers. We call these layers horizons. Each horizon is distinct and has its own characteristics. Soil, Rocks & Minerals 27 © Stephanie Elkowitz • There are 5 major horizons of soil: – O Horizon (Humus) – A Horizon (Topsoil) – B Horizon (Subsoil) – C Horizon (Parent Material) – R Horizon (Bedrock) O Horizon A Horizon B Horizon C Horizon R Horizon Soil, Rocks & Minerals 28 © Stephanie Elkowitz O Horizon A Horizon O Horizon B Horizon A Horizon B Horizon C Horizon C Horizon R Horizon Soil, Rocks & Minerals 29 © Stephanie Elkowitz • The very top layer of soil is called the O horizon. • This layer is mostly made of leaf litter and decomposed organic matter. We call the decomposed organic matter humus. • For this reason, the O horizon is also called humus. Soil, Rocks & Minerals O Horizon 30 © Stephanie Elkowitz • The second layer is called the A horizon or topsoil. • When we talk about soil types, we often are referring to the soil in this layer. • This layer is made of mineral and rock particles mixed with humus. • This is the primary layer where plants grow and animals live. Soil, Rocks & Minerals 31 A Horizon © Stephanie Elkowitz • The third layer is called the B horizon or subsoil. • This layer is mostly made of clay and mineral deposits. • When water drains through the topsoil, it carries minerals with it. When the water moves through the subsoil, the minerals are left behind. This process is called leaching. Soil, Rocks & Minerals B Horizon 32 © Stephanie Elkowitz • Sometimes a lightcolored region of soil forms at the bottom of the A horizon. This is where minerals are “picked up” and carried to the subsoil. Some texts assign this lightcolored region as a separate horizon called Horizon E. Soil, Rocks & Minerals A Horizon B Horizon 33 © Stephanie Elkowitz • The fourth layer is called the C Horizon. • This layer is made of slightly broken up or weathered rock. • The rock in this layer is considered to be the parent material to soil. There is no organic matter in this layer. Soil, Rocks & Minerals 34 C Horizon © Stephanie Elkowitz • The bottom layer is called the R horizon or bedrock. • Bedrock is solid rock. Over time, bedrock will weather or break down, forming the nonorganic (inorganic) particles that make up soil. • Some text do not include bedrock as part of soil but we will consider it because it is important to the formation of soil. Soil, Rocks & Minerals 35 R Horizon © Stephanie Elkowitz • Images obtained from commons.wikimedia.org courtesy: wilson44691, wpsopo, Malene Thyssen, Lyokoi88, En-casede-solei, michael linnenbach, Jarek Tuszynski, Luid Miguel Bugallo, Mikenorton, luca galuzzi, phillip halling, slim sepp, Matthew hatten, wilson biggs • Other images obtained from the Public Domain • Clipart by: – Stephanie Elkowitz – www.mycutegraphics.com – www.mysweetclipart.com 36 © Stephanie Elkowitz