Earth’s Structure Forces on Earth’s Surface Forces Inside Earth Core Concepts 2.3, 2.4, 2.5; p. 22-27 MyWorld Geography Earth’s Structure Earth’s structure is made up of different parts above and below its surface. These parts are the core, mantle, crust, atmosphere, landforms, and water. atmosphere Outer core Inner core mantle water landforms Earth’s Structure Earth’s Core- a sphere of very hot metal at the center of Earth that has temperatures greater than 5000 degrees F. The inner core is solid, while the outer core is hot liquid metal. Mantle- thick, rocky layer around the core with temperatures greater than 3,300 degrees F. It is solid but its temperature allows it to flow like fluid. Crust-the thin layer of rocks and minerals that surrounds the mantle and includes the land areas where people live as well as the ocean floor. Earth’s Structure Atmosphere- a thick layer of gases or air that includes life-giving oxygen and acts like a blanket by holding in heat from the sun, which makes life possible. Landforms- 25% of the Earth’s surface with many didn’t shapes and types and are formed by processes beneath Earth’s surface that push Earth’s crust up. Water- 75% of Earth’s surface which forms a layer above Earth’s crust and holds 97% of Earth’s water. This water is salty. Forces on Earth’s Surface Key Ideas Forces such as wind, water, and ice shape Earth’s surface These forces produce a variety of different landforms Forces on Earth’s surface wear down and reshape the land and help create the landforms we see around us. Key Terms Weathering Valley Erosion Deposition Plateau Plain Delta Wearing Away Earth’s Surface Weathering- is a process that breaks rocks down into tiny pieces. Rainwater or acids carried by rainwater dissolves rocks in Chemical Weathering. Moving water, ice, or sometimes wind breaks rocks into little pieces is called Mechanical Weathering. Weathering helps create soil, which is made from tiny pieces of rock combined with decayed animal and plant material. Soil and pieces of rock undergo erosion, which is a process in which water, ice, or wind removed small pieces of rock. Soil is required to sustain plant and animal life, and for agriculture and is very importing to human settlement patterns. Shaping Landforms Weathering and erosion have shaped many of Earth’s landforms including mountains and hills. Mountains are wide at the bottom and rise steeply to a narrow peak or ridge. Hills are lower than mountains and often have rounded tops. An area in which a certain type of landform is dominant is called a landform region. Rebuilding Earth’s Surface Deposition- is the process of depositing eroded material carried by water, ice, or wind and creates landforms. Plains- or large areas of flat or gently rolling land are often formed by the deposition of material carried downstream by rivers. Forces Inside Earth Key Ideas Movements of hot, soft rock in Earth’s mantle affect Earth’s surface, forming volcanoes and pushing continents together or apart. Key Terms Plate tectonics Plate Magma Fault Forces Inside Earth Plate tectonics is a theory that states that Earth’s crust is made up of huge blocks called plates. Plates include continents or parts of continents along with parts of the ocean floor. Magma is molten, nearly melted, rock that act as a conveyor belt moving the plates in different directions. This movement slowly builds mountains; when 2 plates of crust push against each other, the pressure makes the crust bend to form steep mountains. Earthquakes and Volcanoes Earthquakes occur when plates slide against each other. Earthquakes happen most often occur at seams in the Earth’s crust called faults which are near the plates. Movement of plates creates great pressure inside Earth which sometimes forces magma up through Earth’s crust which forms volcanos. Volcanos spew magma from inside Earth and is called lava, which forms new land forms when the lava cools. Natural Hazards Volcanoes and earthquakes are examples of natural disasters, also known as natural hazards. Other natural hazards include hurricanes, tornados, landslides, and floods. These events threaten lives and property, but people can take steps to prepare.