Understanding Different Types of Maps and Projections
Types of Maps
Introduction
In geography, maps are essential tools for researchers, cartographers, students, and others to study the Earth or specific regions.
What is a Map?
Maps are visual representations of the Earth’s surface. They can be general reference maps showing landforms, political boundaries, water bodies, and city locations. Thematic maps focus on specific topics like rainfall distribution or disease prevalence. With the rise of Geographic Information Systems (GIS), thematic maps are becoming increasingly important.
Different Types of Maps
Political Maps
Political maps depict state and national boundaries, along with cities of varying sizes. An example is a map showing the 50 U.S. states and their borders.
Physical Maps
Physical maps illustrate the physical landscape features of a place, such as mountains, rivers, and lakes. Colors and shades represent elevation changes, with green typically indicating lower elevations and brown representing higher elevations.
Topographic Maps
Similar to physical maps, topographic maps show physical landscape features but use contour lines instead of colors to depict elevation changes. Closely spaced lines indicate steep terrain, while widely spaced lines represent flatter areas.
Climate Maps
Climate maps provide information about an area’s climate, such as climatic zones, snowfall amounts, or average cloudy days. Colors are often used to differentiate climatic regions.
Economic or Resource Maps
Economic or resource maps display the types of economic activity or natural resources present in an area using symbols or colors. For instance, a map of Brazil might use colors to represent agricultural products, letters for natural resources, and symbols for industries.
Road Maps
Road maps are widely used and show major and minor highways, roads, airports, cities, and points of interest like parks and monuments. Major highways are typically depicted as wider red lines, while minor roads are narrower and lighter in color.
Thematic Maps
Thematic maps focus on a specific theme or topic, using background information like rivers or cities as reference points. Examples include maps showing population density, election results, or language distribution.
Thematic Maps Through History
Thematic maps emerged in the mid-17th century after the development of accurate base maps.
Projections and Scale
Projections
Since the Earth is spherical, projections are used to represent it on flat maps.
Planar Projection
The Earth’s surface is projected onto a plane tangential to a point, resulting in a circular projection with concentric parallels. It is often used to represent the poles.
Cylindrical Projection
The Earth is projected onto a cylinder, creating a rectangular projection with perpendicular meridians and parallels. This projection is suitable for representing the entire world.
Conic Projection
The Earth is projected onto a cone, resulting in a fan-shaped projection with straight meridians converging at a point and circular parallels. It is commonly used for mid-latitude areas.
Scale
Scale represents the proportional relationship between the actual size of an object or area and its size on a map.
Numerical Scale
A fraction indicating the ratio between map distance (numerator) and actual ground distance (denominator). For example, a scale of 1:50,000 means that one unit on the map represents 50,000 units on the ground.
Linear Scale
A line divided into equal parts used to directly measure distances on a map. By measuring the distance between two points with a ruler and applying the linear scale, you can determine the actual ground distance.