Chapter 8:Mapping Earth’s Surface

TopographyThe 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.

Landform Elevation Relief

Comparing and Contrasting

As you read, compare and contrast the characteristics of landforms by completing a table like the one below.

Plain Low Low

Mountain High High

Plateau High Low

Characteristics of Landforms

Maps and Globes

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

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 measures23.5 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 cmd = 5,875,000 cm

Scales and Ratios

Scales and Ratios

Practice ProblemA 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 SurfaceThe 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 ProjectionsA 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 ProjectionsAn equal-area projection shows areas correctly, but distorts some shapes around its edges.

Map ProjectionsA 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 TopographyMapmakers 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

Yellow; points below 1,200 feet.

Reading Maps:

What color are the lowest points on the map? What range of elevations do these points represent?

Mapping Elevation Data

Red; 1,500 feet or above.

Reading Maps:

What color are the highest points on the map? What range of elevations do these points represent?

Mapping Elevation Data

1,300 feet

Applying Concepts:

What is the elevation of the contour line labeled A?

Mapping Elevation Data

Valley; contour lines curve uphill.

Inferring:

Is the area between B and C a ridge or a valley? How can you tell?

Mapping Elevation Data

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.

Interpreting Data:

Describe how elevation changes along the trail from point D to point C.