Chapter 8: Mapping Earth’s Surface

Topography The route of the Lewis and Clark expedition crossed regions that differed greatly in elevation, relief, and landforms.

Elevation- height above sea level Relief- difference in elevation between the highest and lowest parts of an area Landforms- feature of topography formed by the processes that shape Earth’s surface

Types of Landforms There are three main types of landforms: plains, mountains, and plateaus.

Types of Landforms A large area of land where the topography is made up of mainly one type of landform is called a landform region.

Comparing and Contrasting As you read, compare and contrast the characteristics of landforms by completing a table like the one below. Characteristics of Landforms Relief Landform Elevation Plain Low Low Mountain High High Plateau High Low

Maps and Globes Maps and globes are drawn to scale and use symbols to represent topography and other features on Earth’s surface.

Scales and Ratios A ratio compares two numbers by division. For example, the scale of a map given as a ratio is 1:250,000. At this scale, the distance between two points on the map measures 23.5 cm. How would you find the actual distance? 1. Write the scale as a fraction. 2. Write a proportion. Let d represent the distance between the two points. 3. Write the cross products. 1 X d = 250,000 X 23.5 cm d = 5,875,000 cm

Scales and Ratios Practice Problem A map’s scale is 1:25,000. If two points are 4.7 cm apart on the map, how far apart are they on the ground? 117,500 cm or 1.175 km; (1 X d = 25,000 X 4.7 cm) or (25,000 X 4.7 cm)

An Earth Reference System Distances around circles are measured in degrees.

An Earth Reference System The equator and prime meridian divide Earth’s surface into hemispheres.

Locating Points on Earth’s Surface The lines of latitude and longitude form a grid that can be used to find locations anywhere on Earth.

Locating Points on Earth’s Surface Every point on Earth’s surface has a particular latitude and longitude.

Map Projections A Mercator projection is based on a cylinder with grid lines that has been flattened. On a Mercator projection, lines of longitude are parallel, so shapes near the poles are distorted.

Map Projections An equal-area projection shows areas correctly, but distorts some shapes around its edges.

Map Projections A conic projection is based on a cone that covers part of Earth and is then rolled out flat. A conic projection’s grid is formed from straight lines of longitude and curved lines of latitude.

Satellite Mapping Google Earth

Mapping Earth’s Topography Mapmakers use contour lines to represent elevation, relief, and slope on topographic maps.

Reading a Topographic Map To read a topographic map, you must familiarize yourself with the map’s scale and symbols and interpret the map’s contour lines – change in elevation from one contour line to the next.

Mapping Elevation Data The map shows the elevation data points on which the contour lines are based. Study the map and the map key, then answer the questions.

Mapping Elevation Data Reading Maps: What is the contour interval on this map?

Mapping Elevation Data Reading Maps: What color are the lowest points on the map? What range of elevations do these points represent? Yellow; points below 1,200 feet.

Mapping Elevation Data Reading Maps: What color are the highest points on the map? What range of elevations do these points represent? Red; 1,500 feet or above.

Mapping Elevation Data Applying Concepts: What is the elevation of the contour line labeled A? 1,300 feet

Mapping Elevation Data Inferring: Is the area between B and C a ridge or a valley? How can you tell? Valley; contour lines curve uphill.

Mapping Elevation Data Interpreting Data: Describe how elevation changes along the trail from point D to point C. At point D, elevation is above 1,500 feet. It then decreases to about midway along the trail where elevation is less than 1,400 feet. Elevation then increases again to point C, which is above 1,500 feet.