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Directory > Maps > Topographic (11)

An Introduction to Topographic Maps

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A map is a representation of the Earth or part the earth. Traditionally, maps have been printed on paper. If a printed map is scanned and a computer file created, that file may be called a digital raster graphic.

The distinction of a topographic map is that the shape of the Earth's surface is shown by contour lines. Contours are imaginary lines that join points of equal elevation on the surface of the land above or below a reference point such as sea level. Contours make it possible to measure the depths of the ocean bottom, height of mountains, and steepness of slopes.

A topographic map will also include symbols that represent dirrerent things and features as streets, buildings, streams, and wooded areas. Symbols are being constantly refined to better relate to the items they represent. This is to improve the appearance or readability of the map, or to reduce production cost.

Consequently, within the same series, maps may have slightly different symbols including built-up areas, roads, intermittent drainage, and possibly type styles.

Interpreting the colored lines, areas, and symbols will be the first step in learning to use topographic maps. Features are shown as points, lines, or areas, depending on their extent and size. Individual houses may be shown as small black squares. Larger buildings may be shown as the actual shape. In densely populated or built-up areas, individual buildings are sometimes omitted and shown as a tinted area. On some maps, the tinted area will show post offices, churches, city halls and other landmark buildings.

The first features usually noticed on a topographic map are vegetation (green), water (blue), some information added during update (purple), and densely built-up areas (gray or red).

The lines shown on the map may be straight, curved, solid, dashed, dotted, or in any combination. The colors of the lines usually indicate similar kinds or classes of information: brown for topographic contours; blue for lakes, streams, irrigation ditches, etc.; red for land grids and important roads; black for other roads and trails, railroads, boundaries, etc.; and purple for features that have been updated using aerial photography, but not verified by a field cartographer.

Various point symbols are used to depict features such as buildings, campgrounds, springs, water tanks, mines, survey control points, and wells.

Names of places are shown in a color corresponding to the type of place. Some features are identified by labels, such as " Electrical Sub-station" or "Golf Course".

Contours Showing Ground Configuration

Contours are shown on Topographic maps in brown lines of different widths. Each contour is a line of equal elevation; therefore, contours never cross. They show the general shape of the terrain. To help the user determine elevations, index contours (usually every fourth or fifth contour) are wider. The narrower intermediate and supplementary contours found between the index contours help to show more details of the land surface shape. Contours that are very close together represent steep slopes. Widely spaced contours, or an absence of contours, means that the ground slope is relatively level. The elevation difference between adjacent contour lines, called the contour interval, is selected to best show the general shape of the terrain. A map of a relatively flat area may have a contour interval of 10 feet or less. Maps in mountainous areas may have contour intervals of 100 feet or more. Elevation values are shown at frequent intervals on the index contour lines to facilitate their identification, as well as to enable the user to interpolate the values of adjacent contours.

Contours showing the measurement of the depths of oceans, seas and other bodies of water (Bathymetric), are generally offshore since they show the shape and slope of the ocean bottom. They are shown in blue or black. Bathymetric contours are shown in meters at intervals appropriate to map scale and coastal profile, and should not be confused with depth curves.

Depth curves are shown where the data are available from hydrographic charts or other reliable sources. Depth figures, shown in blue along the curves, are in feet on older USGS maps and in meters on newer maps. Soundings, individual depth values, may also be shown.



Topographic Maps

Digital collarless and collared topographic maps, standardized digital elevation models (DEMs) and digital ortho quarter quadrangles (DOQQs). Data available for U.S. in any projection.

A good site for topographic map users and outdoor recreation enthusiasts. If you're a hiker, biker, fisherman, hunter, or even a real estate agent, Topozone can be a valuable resource. Topozone claims "every USGS 1:100,000, 1:25,000, and 1:24,000 scale map for the entire United States".

They claim to have "every USGS 1:100,000, 1:63,360, 1:25,000, and 1:24,000 scale topographic map for the entire United States". Search for a place and the results are returned listing place, county, state, type (town/city/hill), elevation USGS Quad, and latitude & longtitude. Click on "Place" of your choice for the map.

Historic Topographic Maps of California

You will find historic topographic quadrangles produced by the U.S. Geological Survey between 1895 to the present. there is also selected editions for maps covering the greater San Francisco Bay. Using the Gazetteer Search you can search for a place name to determine on which quadrangle your feature is located.You may also want to visit the UC Berkely Earth Sciences & Map Library Home   [New Window]

Canada's national topographic mapping agency, the Centre for Topographic Information of Natural Resources Canada. The National Topographic Data Base, the Centre for Topographic Information in Ottawa produces topographic maps at scales of 1/50 000 and 1/250 000.

Learn about Canada's topographic maps. The National Topographic System provides general-purpose topographic map coverage of Canada. These maps depict in detail ground relief (landforms and terrain), drainage (lakes and rivers), forest cover, administrative areas, populated areas, transportation routes and facilities (including roads and railways), and other man-made features.

Try this site to find topographic maps and related base maps and imagery. The categories are paper maps, ditigal maps and general information (educational materials, resources and publications on cartography).

Geography, both cultural and physical, is extremely important for understanding the ancient world. Eastern Mediterranean, Greece, Italy and Germany.

Directories and Guides

This page has links to topographic maps which have been selected to illustrate common geologic processes, cultural features and topographic map symbols. Topics are: Cultural Features and Map Symbols, Igneous Activity, Mass Movement, Streams, Underground Water, Glaciers, Wind, Waves and Currents, Geologic Structures and Ocean Basins.

Learn to read topo maps with the links to examples of landforms depicted on topographic maps. Examples include Geologic Structures, Igneous Activity, Mass Movement, Streams, Underground Water, Glaciers, Wind & Waves and Currents.

Topographic Maps, The Basics. Produced by the Centre for Topographic Information of Natural Resources Canada are used for a wide variety of applications, from camping, canoeing, fishing and hiking to urban planning, resource development and surveying. Why? Because they represent the earth's features accurately and to scale, on a two-dimensional surface.

An introduction to topo maps. Explains what a topographic map is, how to read topographical maps and explains the symbols used in topographic mapping.

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Last Updated: December 3, 2005