geographic maps, maps

LEARNING OBJECTIVES

By the end of this lesson, you should be able to:

• Define map
• Define scale
• Describe features of maps
• Describe types of maps
• Describe uses of maps

A map is a representation on a flat surface of all or a part of the surface of the earth or other celestial body like the moon. It is important to note that maps are much smaller in terms of size compared to the actual area of the surface of the earth that they represent. This is made possible by the use of a scale.

In maps, scale refers to the ratio of distance on a map to the actual distance on the ground. A map can also have a numerical scale, for example, 1: 50,000 which means that 1cm on the map represents 50,000cm of actual space.

Despite the fact that the earliest known maps are of the heavens, territory’s geographic maps have a long tradition and they have been existing since the ancient times.

Maps give us information about the earth/world in a visual and simple way. Maps help you understand the world by showing shapes and sizes of countries, distances between places, and locations of features. Maps can also show the distribution of things over earth like settlement patterns. Some maps can also show exact locations of streets and houses in a neighborhood.

Map makers are called cartographers. Cartographers create maps for different purposes. For example, road maps are used by vacationers to plot routes of their trips. Meteorologists (scientists responsible for studying weather) use weather maps for preparing forecasts.

FEATURES OF MAPS

The most common features of maps are; scale, grid, and symbols.

The scale of a map shows the relationship between the area or distances on a map and the actual area or distance on earth. Scale can be expressed through the following means; verbal scale, graphic scale, or representative fraction. The most common graphic scale is called bar scale. It looks like a ruler. It is a horizontal line marked in kilometers, miles, or another unit of measuring distance.

The verbal scale involves a sentence relating distance on a map to actual distance on earth. For example, "one centimeter represents one mile" or "one inch represents five kilometers.

The representative fraction lacks specific units. It is represented as a ratio or fraction. For example, 1/1,000,000 or 1:1,000,000. This means that a unit of measure on the map equals one million of that unit on actual earth. Therefore, 1cm on a map represents one million centimeters on earth.

Cartographers apply symbols for representing geographic features. For example, some lines represent boundaries, highways, roads, and rivers. Black dots on the other hand are used to represent cities.

Some maps contain grid patterns. This involves a number of crossing lines creating rectangles or squares. The grid is to help you locate places on the map. The grid is mainly made up of longitude and latitude lines.

TYPES OF MAPS

Maps may be classified on different basis as discussed below;

Classification of maps on the basis of their scales:

• Small Scale Maps. These are maps that represent large areas using small sizes. For example, these maps may have a scale of 1cm representing 500 km. examples of these maps include wall maps and those found in school atlas.
• Large Scale Maps. These are those maps that are used to represent very small areas. For example, these maps may have a scale of 1cm representing 2 meters. Examples of these maps include town plans and cadastral maps that show boundaries of properties that are landed.

Classification of maps on the basis of their aims and objectives

• Physical maps. These are maps that show the earth’s relief features with the help of contours, hachures or color tints that are between contour lines, for example, seas, lakes, rivers and other water bodies in blue, plains in green, plateaus in yellow among others.
• Political maps. These are maps that represent a world’s visual picture, or a country or a continent by bold boundary lines.
• Distribution/ Statistical maps. These are maps that are related to statistical data. They may show physical elements such as rainfall, air pressure and relief and they can also be used to show economic and social data like trade, industry, population, transport and settlements.
• Topographic maps. These maps show the earth’s physical features together with cultural aspects such as transportation and settlement facilities. These maps are mostly applied by geographers and military experts.
• Geological maps. These are maps that show the rock formations, the ages of these rocks, their structures, their mineral resources and many more. They are mainly applied in mining and engineering.
• Geomorphological maps. These are maps that show the physical features of the earth, their relationship with land, water among others.
• Cadastral maps. These are maps that are created by the agencies of the government for revenue purposes. They are used to show boundaries of landed fields, buildings or properties.
• Bathymetric maps. These are navigation maps showing the sea floor’s relief and they are very useful for mariners.
• Aeronautical maps.  These are maps that show physiographical features of the airports, airways and land for use by pilots.

USES OF MAPS

Below are some of the general uses of the types of maps explained above:

1. They bring out at a glance the various geographical elements.
2. They reveal the relationships between different geographical elements.
3. For the investigation as well as the exploration of resources.
4. For the purposes of planning, optimal utilization as well as the development of resources.
5. For seeing the very many dimensions of a region at a single time.

SUMMARY

• A map is a representation on a flat surface of all or a part of the surface of the earth or other celestial body like the moon.
• Map makers are called cartographers.
• The most common features of maps are; scale, grid, and symbols.