Representing Earth’s Surface

Chapter 1Section 3

Determining Location

Latitude and longitude are lines on the globe that are used to determine location.• Latitude is distance north or south of the equator, measured in

degrees.• The middle latitude, at 0 degrees, is the equator

• Longitude is distance east or west of the prime meridian, measured in degrees.• The middle longitude, at 0 degrees, is the prime meridian

Royal Observatory in Greenwich, London

Globes

Advantages:• Accurate shapes and sized of

continents

Disadvantages:• Too small to show details

Projection Maps: Mercator Projection

Advantages• Rectangular• Longitude lines are parallel• Directions shown accuratelyDisadvantages• Sizes and distances distorted

Projection Maps: Robinson Projection

Advantages• Most distances, sizes, and

shapes are accurateDisadvantages• Distortion around edges of maps

Discuss: How do shapes in the continents differ between the Mercator and the Robinson maps?

Projection Maps: Conic Projection

Advantages:• Great accuracy over small areas• Used for road and weather maps

Disadvantages:• Lots of distortion on most of the

map

Projection Maps: Gnomonic Projection

Advantages:• Reliably shows the shortest

distance between two points

Disadvantages• Exact distances and directions

distorted

Topographic Maps

Topographic maps represent Earth’s surface in three dimensions; they show elevation, distance directions, and slope angles.

• Contour lines are lines on a topographic map that indicate an elevation. (hachure marks)

• Contour interval is the distance in elevation between adjacent contour lines.

Topographic MapsDiscuss:

Where is the land flattest?

Where is the land steepest?

How do the contour lines show a stream?

Geologic Maps

A map that shows the type and age of exposed rock

GPS

GPS

• Satellites and computers allow scientists to more precisely analyze Earth’s physical properties.

• Can detect latitude, longitude, altitude/elevation, speed, and direction• Three satellite signals are detected by a receiver. The distance from the

satellites to the receiver is calculated, and the location is determined using the triangulation method. A fourth signal is then used to mathematically determine exact position.

Review

1. Describe the two sets of lines that are used on globes and some maps

2. What happens to images from a globe when they are transferred to a flat surface?

3. What is the purpose of contour lines on a topographic map?