EXPLORING EARTH S SURFACE. Lesson 4

Transcription

1 EXPLORING EARTH S SURFACE Lesson 4

2 Introduction Lewis and Clark In 1804, an expedition set out from near Saint Louis to explore the land between the Mississippi River and the Pacific Ocean, The United States had just purchased part of this vast territory from France. Few had traveled far to the west. Led by Meriwether Lewis and William Clark, the expedition first traveled up the Missouri River. Then the group crossed the Rocky Mountains and followed the Columbia River to the Pacific Ocean.

3 Big Question If you were going on an expedition to explore unknown territory, what supplies would you bring with you and why? Choose only five items.

4 Vocabulary Words Topography-is the shape of the land; it includes the area s elevation, relief, and landforms Elevation-the height above sea level of a point on Earth s surface Relief-the difference in elevation between the highest and lowest parts of an area Landform-is a feature of topography, such as a hill or valley, formed by the processes that shape Earth s surface; different landforms have different combinations of elevation and relief Plain-is a landform made up of nearly flat or gently rolling land with low relief Mountain-is a landform with high elevation and high relief

5 Mountain base-is the base of a mountain, it can cover an area of several square kilometers or more Mountain range-is a group of mountains that are closely related in shape, structure, area, and age Plateau-a landform that has high elevation and a more or less level surface; it is rarely perfectly smooth on top; rivers and streams may cut into the plateau s surface Landform region-a large area of land where the topography is made up mainly of one type of landform

6 What Does the Topography of an Area Include? Elevation The height above the sea level of a point in the Earth s surface When Lewis and Clark started their journey, they were about 140 meters above the sea level By the time they reached Lemhi Pass in the Rocky Mountains, they were more than 2,200 meters above sea level Relief The difference in elevation between the highest and lowest parts of an area Early in their journey, they encountered flat or rolling land that had low relief, or small differences in elevation In the Rocky Mountains, they crossed huge mountains separated by deep valleys These areas had high relief, or great differences in elevation

7 Landforms If you followed the route of their expedition, you would see many differences in landforms. A landform is a feature of topography, such as a hill or valley, formed by the process that shapes Earth s surface Different landforms have different combinations of elevation and relief

8 CRITICAL THINKING The word topography is a combination of two Greek words: topos that means place and graphia that means to write. How does the word s origin relate to its scientific meaning?

9 What Are the Main Types of Landforms? Landforms vary greatly in size and shape They include level plains extending as far as the eye can see, rounded hills that you could climb on foot, and jagged mountains difficult to hike through Three major types of landforms are: plains, mountains, and plateaus

10 Types of Landforms Plains Made up of nearly flat or gently rolling land with low relief A plain that lies along the seacoast is known as a coastal plain In North America, a coastal plain extends around the continent s eastern and southeastern shores Coastal plains have both low elevation and low relief A plain that lies away from the coast is called interior plain Interior plains are often low and have low relief, but their elevations can vary The broad interior plains of North America are called the Great Plains

11 Mountains A mountain is a landform with high elevation and high relief A mountain s base can cover an area of several square kilometers or more Mountains usually exist as part of a mountain range A mountain range is a group of mountains that are closely related in shape, structure, area, and age The different mountain ranges in a region make up a mountain system The Bitterroot Mountains are one mountain range in the mountain system known as the Rocky Mountains Mountain ranges and mountain systems in a long, connected chain form a larger unit called a mountain belt The Rocky Mountains are part of a great mountain belt that stretches down the western sides of North America

12 Rocky Mountains The Rocky Mountains stretch more than 3,000 miles (4,830 km) from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States. The range's highest peak is Mount Elbert located in Colorado at 14,440 feet (4,401 m) above sea level.

13 LEARN MORE ABOUT THE ROCKY MOUNTAINS

14 Plateau A plateau is a landform that has high elevation and a more or less level surface (low relief) It is rarely perfectly smooth on top Streams and rivers may cut into its surface The Columbia Plateau in Washington State is an example The Columbia River, which Lewis and Clark expedition followed, slices through this plateau The many layers of rock that make up the Columbia Plateau rise as high as 1,500 meters

15 Palouse River Canyon

16 Basalt fractures in the plateau

17 Landform Regions A landform region is a large area of land where the topography is made up mainly of one type of landform The Great Plains and the Rocky Mountains are examples of major landform regions in the U.S.A. All of the land in one major landform region tends to have much in common. For example, the land of the Atlantic Coastal Plain is generally of low elevation and relief There are different landform regions: coastal plains, interior plains or lowlands, mountains, plateaus or uplands, basins

18 Videos about Landforms

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20 Assess Place these features in order from smallest to largest: mountain system, mountain range, mountain belt, and mountain Answer-mountain, mountain range, mountain system, mountain belt

21 Questions 1.) The topography of an area includes:,, and 2.) How do the elevations of hills, valleys, and mountains compare? 3.) Which two landforms are relatively flat features with low relief? 4.) How is a plain different from a plateau? 5.) Which landform has high elevation and high relief? 6.) Which landform region would have long ocean beaches? 7.) In which landform region could you visit many ski resorts?