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General World Cultures Chapter 2- Physical Geography glacier- a huge, moving mass of ice erosion- the wearing away of the Earth’s surface by wind or water delta- a flat, sandy area where a river enters an ocean plain- a flat landform plateau- a high, flat landform map projection- a way to draw the curved areas of the Earth on a flat surface tropical- related to regions near the equator; a tropical climate is warm and moist fossil fuel- coal, oil, or natural gas that formed over millions of years from the remains of plants and tiny animals renewable resource- a resource that can be replaced as it is used nonrenewable resource- a resource that cannot be replaced by natural resources or is replaced extremely slowly * The Earth is not just a solid ball. It has three separate layers: the crust, the mantle, and the core. * The crust is a thin layer of rock, sand, and soil. It covers the Earth like a skin and even lines the floor of the oceans. * Below the crust is a thick layer of rock called the mantle. The outer part of the mantle is melted but deeper inside it is solid. * At the center of the Earth is the core, which is made up of two metals: nickel and iron. In the outer core the metals are more fluid, but the very heart of the Earth is solid. * The inside of the core is a very busy place. Melted rock and other materials are always flowing and rubbing together. This activity builds up heat and pressure that causes movements in the crust. Sometimes, these movements can be felt as earthquakes. Mountains and volcanoes are created and formed by forces deep in the Earth. Most of the changes happen too slowly for people to notice. A volcanic eruption, however, causes sudden change. Forces deep within the Earth, then, do affect life on the surface. There is no way to stop these forces. The Earth’s Surface * Water covers 70% of the Earth. Therefore, only 30% of the Earth’s surface is visible land. The water is in oceans, lakes, rivers, streams, ponds, and glaciers. Water can also be found underground. * The oceans and seas hold most of the water on the planet. This water is salty, and we cannot drink it or use it for farming. Ocean water evaporates, however, and turn into water vapor. Most of the salt stays behind, and the water vapor becomes part of the air. Wind carries the water vapor over the land, where it may drop back to the Earth as rain or snow. In time, the water flows back to the sea. This process is known as the water cycle. * The atmosphere is the layer of air around the Earth. It is about 1,000 miles thick. It is made up mainly of two gases- nitrogen and oxygen- along with small amounts of other gases. * Water and air are always changing the surface of the Earth. Wind, ice, and flowing water break down rocks. We call this process weathering. Wind and water also carry away bits of rock and soil in a process called erosion. For example, through erosion, a river may wash soil downstream. The soil ends up in a delta. * Weathering and erosion shape the Earth’s surface. They wear mountains down to hills and create valleys and canyons. The create plains and plateaus. Complete the Landforms and Waterbodies Diagram Study on page 17. Map Projections * The Earth, shaped like a ball, has a curved surface. A globe is used to represent this curved surface. Suppose you could remove the outer layer of this globe. Could you smooth it out to make it flat like a map? Not quite. It would stretch and split in many places. * We are going to try an experiment. You will try to cover a round object using a flat piece of paper. Write down your experiences on the piece of paper afterwards. * You can see the problem that mapmakers face when they draw maps of the Earth. A flat map cannot really show the curved surface of the Earth. That is why geographers invented map projections. * There are many different kinds of map projections. Each one shows a different way to draw the curved areas of the Earth on a flat surface. However, all map projections have some distortion. Some of these maps change the shapes of continents or make their sizes look incorrect. In some map projections, the distances between places look wrong. Some of these maps do not accurately show directions (north, south, east, and west). The distortions are more noticeable on maps that show larger areas. A map of the world has much distortion. A map of your town would have almost none. * A Mercator projection shows the true shapes of continents and islands. To make the shapes correct, a Mercator projection stretches the lines of latitude apart. As a result, the map does not show the true sizes of the landmasses. The farther away a landmass is from the equator the greater the distortion. However, a Mercator projection map is a good kind to use for travel on the ocean because it shows directions accurately. * Most maps in geography books are based on the Robinson Projection. This type of projection map shows only small distortions. Only the landmasses near the South Pole and North Pole look distorted. Complete the Geography In Your Life Making Maps on page 19. Rotation and Revolution There are nine planets in the solar system: My Very Easy Method Speeds Up Naming Planets Complete the webquest and accompanying worksheet at the following address: http://teach.fcps.net/trt8/SolarSystem/Planets.htm All of the planets travel around the sun. The Earth is the third planet in orbit away from the sun. It takes a year for the Earth to make a full trip, or revolution, around the sun. * Revolution is one way in which the Earth moves through space. The Earth also spins on its axis in a motion called rotation. The Earth makes one complete rotation in 24 hours. However, the Earth’s axis does not point straight up and down. It is slightly tilted. * During some months, this tilt aims the North Pole a little towards the sun. In these months, the sun shines directly on the Northern Hemisphere for more hours of each day. These are the summer months in the Northern Hemisphere. In the Southern Hemisphere, these are the winter months, because the South Pole is tilted away from the sun. * During the summer months in the Southern Hemisphere, the South Pole is tilted towards the sun. When neither pole is tilted towards the sun, it is spring or fall. The Earth’s tilt and its revolution together cause the changing seasons. Complete the Geographer’s Tool Kit Understanding Latitude and Longitude on pg. 21 Climate Around the World * The weather changes every day. Describe the weather outside today. _______________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ One day it might be warm and sunny, and the next day it might rain. The weather in any one place follows a general pattern, however. For example, Denver, Colorado, can expect some snowfall each winter. Los Angeles, California, can expect warm, dry winds every fall. * Why is climate different from place to place? ___________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ _________________________________________________________________________________________________ Three main factors shape climate. Latitude is one factor. The closer a place is to the equator, the warmer it tends to be. Another factor is elevation. In general, the higher above sea level a place is, the cooler it is. Complete The World: Climate Regions on page 22 Finally, the ocean (an other large bodies of water) plays a part. The temperature of the ocean does not change easily. When cold air blows over the ocean, the air warms up. When hot air blows over the ocean, the air cools down. Therefore, it is the ocean that prevents the extremes of great heat and cold. Therefore, it is the ocean that prevents the extremes of great heat and cold. That is why places near the ocean tend to have milder climates than inland areas. * Some geographers divide the Earth into five climate regions. In the far north and south are the polar regions. Near the poles and the middle of continents are the cool/moist regions. Closer to the equator and near oceans and seas are the warm/moist regions. Here and there are deserts that have a dry climate. Along the equator is the hot, rainy tropical climate region. Using the Earth’s Resources * Anything we use from the Earth is considered a natural resource. Water is a natural resource. Air is another. Without these two natural resources, nothing could live. The plants and animals that we eat are resources. So are rocks, minerals, soil, fossil fuels, and many other things. * Some resources can be replaced as they are used. For example, when we cut down trees for lumber, we can plant new ones to replace them. Trees, then, are renewable resources. Some resources were formed millions of years ago, such as fossil fuels like oil, natural gas, and coal. They cannot be replaced quickly. These are nonrenewable resources. * The Earth’s resources are spread out unevenly. In desert regions, for example, fresh water is scarce. Without water, food is hard to grow. People in these areas may have to trade the resources they have to get food. Most people depend on trade to get at least some of the resources they need. Many desert regions are rich with oil. * In the U.S., most people work in factories and businesses. A lot of natural resources are needed to support this way of life. Factories, power plants, and cars, use a lot of energy. Much of that energy comes from burning fossil fuels. * However, we may soon run out of fossil fuels. Furthermore, burning these fuels does damage to the environment. Cars, factories, and power plants put harmful smoke and gases into the air. Over the years, the air around the world has become dirty and is killing some of our forests. * The smoke and gases have affected the atmosphere high above the Earth, too. The damaged atmosphere may be letting in more of the sun’s harmful rays, which could change the climate of the Earth. Problems such as these are of interest to geographers. Complete Global Issues The Ozone Layer on page 25