An Introduction to Cartography Design and Types

What are maps used for? Maps serve a variety of functions. They are most often used to show: Landforms (physiographic maps and surface maps) Elevation (topographic and bathymetric maps) Trends (weather maps, ocean current maps, population maps, etc)

Examples

Basics of Maps All maps must have: Title Legend Box Scale Directional Arrow Signature and Date (but this is often omitted on weather and topographic maps)

The Globe Basic divisions on world map are lines of latitude and longitude Latitude lines run ________ and never meet. They mark your position relative to the equator Each degree of latitude is equal to about 70 miles (112 km) East-west

The Globe Longitude lines run north and south and intersect ___________. They mark your position relative to Greenwich, England (prime meridian - 0º). “East” longitude lines are east of the prime meridian – “West” are west of the PM The distance separating lines of longitude varies with your distance to the poles. at the poles

Practice with Latitude and Longitude On your printed map find the location of the following cities: Yellowknife (62 N 114 W) Melbourne (37 S 145 E) Tripoli (32 N 13 E) Guayaquil (2 S 80 W)

The Globe The globe is one of the best ways to represent earth’s surface since both are spheres Limits distortions seen in flat projections

Distortions on World Maps Take a look at Antarctica. Compare what you see in both maps. Now predict where what else would be distorted.

Ways to Minimize Distortions Since all flat maps have some degree of distortion, many different map “projections” have been invented to cut down on the distortion. These include the Mercator, Robinson, Conic and Gnomonic Projections

The Mercator Projection This is the oldest and most common projection. It preserves DIRECTION but distorts shape and distance (especially at poles) It does this by shrinking latitude distances at the equator and increasing it at the poles Commonly used by sailors for navigation

The Mercator Projection

The Robinson Projection The Robinson Projection was developed in the 1960s for Rand McNally (largest map maker in the world) It uses curved lines of longitude and displays the poles as lines instead of points Causes great distortion at the poles, but is very accurate in terms of distances and shapes in all other areas

The Robinson Projection

Mercator vs. Robinson Compare the sizes of Greenland

Conic and Gnomonic Projections Made by projecting images onto a flat piece of paper either wrapped around the earth or laid flat along the pole Good for small distances, but creates enormous distortions over large distances

Conic Projection

Gnomonic Projection

Summing Up Maps are used to represent the earth’s surface and its features Due to the difficulty in representing a spherical earth on a flat surface, numerous projections have been developed in mapping