Types of Maps
Cartographers make many different types of maps, which can be divided into two broad categories: general reference and thematic.
General Reference
These maps show general geographic information about an area, including the locations of cities, boundaries, roads, mountains, rivers, and coastlines. Government agencies such as the U.S. Geological Survey (USGS) make some general reference maps. Many are topographic maps, meaning that they show changes in elevation. They show all the hills and valleys in an area. This is useful to everyone from hikers trying to choose a route to engineers trying to determine where to build highways and dams.
- Topographic (topo) maps show physical features of a given area of land.
- Geologic maps show bedrock formations like granite or limestone, sediment deposited by glaciers or rivers, and structures like folds and faults.
Thematic
These maps display distributions, or patterns, over Earth’s surface. They emphasize one theme, or topic. These themes can include information about people, other organisms, or the land. Examples include crop production, people’s average income, or where different languages are spoken.
Sanborn maps were created to assist fire insurance companies as they assessed the risk associated with insuring a particular property. They show information such as the outline of each building, the size, shape and construction materials, heights, and function of structures.
source: National Geographic Resource Library, Encyclopedic Entry: Map.
GIS Maps
Many thematic maps are now made with the help of geographic information system (GIS) technology. GIS are computer systems that capture, store, and display data related to positions on Earth’s surface. This technology combines information from maps with other data about people, the land, climate, farms, houses, businesses, and much more, allowing multiple sets of data to be displayed on a single map. Many industries and governments use GIS technology for analysis and decision making. For example, GIS data helps officials determine which streams are most in danger of being polluted. It can also help a business decide where to locate a new store.
source: National Geographic Resource Library, Encyclopedic Entry: Map.
Topographic
The distinctive characteristic of a topographic map is the use of elevation contour lines to show the shape of the Earth's surface. Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the ocean bottom, and the steepness of slopes.
source: USGS Mapping, Remote Sensing, and Geospatial Data FAQs
