Table Of Contents: Earth's Surface
1. Lesson Objectives
2.1. How Does The Earth's Surface Change?
3.1. The Earth's Surface
4.1. A Close-Up of The Earth's Surface
4.2. Changes Over Time
5.1. The Earth
The Earth is made up of three main layers - crust, mantle and core. We live on the outer layer of the Earth called the crust. The Earth's crust is made up of many different rocks. The layer beneath the Earth's crust is called the mantle. The Earth's mantle is made of igneous and metamorphic rocks.
5.2. Earth's Core
The innermost layer of the Earth is called the core. The Earth's core is made of metal. The Earth's core is hot enough to melt but the center of the core is packed together so tightly that it remains a solid. The outer section of the Earth's core however is hot, thick liquid.
5.3. Earth Inside and Out Interactive Activity
Earth's surface has many shapes and features, known as landforms. They include mountains, canyons, deltas, hills, valleys, and more. A topographic map shows the elevation of these landforms.
5.5. Examples of Landforms
Examples of landforms include glaciers, rivers, lakes, valleys, hills, mountains, coasts and oceans.
5.6. Erosion and Deposition
Changes on the Earth's surface are caused in part by weathering and erosion. Erosion is the wearing away of the Earth's surface by rain, wind, snow, and ice. Deposition is the laying down of pieces of Earth's surface, such as rocks and sand. Over time, whole landscapes can be changed by erosion and deposition.
5.7. Landforms Interactive Matching Activity
The Earth's surface changes constantly because of wind, water, temperature changes, and living things. Landforms can change due to weathering which is the process of breaking rocks into smaller pieces. There are two types of weathering - physical and chemical.
5.9. Physical Weathering
One way physical weathering takes place when water and ice break rocks down into smaller pieces. This happens by freezing and thawing. Physical weathering only changes the size of the rock.
5.10. Chemical Weathering
Chemical weathering not only changes the size of rocks but also causes them to change into different materials. During chemical weathering the rocks are broken down by the actions of chemicals in the air or water.
Soil covers most of Earth's land. It is a mixture of sediments of weathered rocks, nonliving materials, and decayed plants and animals. Over time, three layers of soil develop. Topsoil is made mostly of decaying plant and animal remains (humus). Subsoil contains minerals and small rocks. Bedrock is mostly solid rock.
5.12. Physical and Chemical Weathering Interactive Activity
5.13. Earth's Plates
The outermost layer of the Earth's crust is called the lithosphere. This layer is broken down into small and large sections called plates. These plates move slowly and might run into each other, pull apart, or grind past each other. As these plates move, they can cause changes to the Earth's surface. These changes include earthquakes, volcanoes, and the formation of mountains and valleys.
Earthquakes cause rapid changes to the Earth's surface. An earthquake is a sudden shift in the Earth's crust that causes the ground to shake and vibrate violently. They most often occur where plates meet on land or under the ocean.
Magma is hot, melted rock found beneath the Earth's surface. When pressure builds up, magma erupts though the Earth's crust. Volcanoes are openings in the Earth's crust where the magma comes out. Melted rock that comes above the Earth's surface is called lava. Volcanoes can also cause rapid changes to the Earth's surface.
5.16. Volcanic Islands
Volcanoes can form on continents or they can build from the ocean floor forming volcanic islands. The Hawaiian Islands were formed this way.
5.17. Types of Natural Processes Matching Interactive
5.18. How Does The Earth's Surface Change?
5. Virtual Investigation
6.1. Weathering and Erosion
7.1. How Does The Earth's Surface Change?
7. Lesson Summary
8.1. How Does The Earth's Surface Change?