THE BASICS:

The formal name for the type of map you are studying is "USGS 7.5 Minute Topographic Quadrangle". You may also see the phrase "7.5 Minute Topo Quad", "7.5 Minute Quad Map" or sometimes just "topo map" or "topo quad" when the size is understood to be 7.5 minutes.

The 7.5 Minute quad maps that you are studying covers 7.5 by 7.5 minutes on the surface of Earth using the latitude and longitude coordinate system. There are 54,000 7.5 minute topo maps that cover the contiguous United States and Hawaii. Because of the size of Alaska, it is mapped at 15 minutes of latitude and includes 2,700 maps. A 7.5 minute topo quad printer on paper is about 24 x 28 inches in size, however most quad maps are also digital.

Click on this link to view a scanned topographic map.

Zoom in and out to examine the map, particularly the detail shown. To zoom in and out, after the map has displayed, move your mouse to the map and leave it there for a moment. After a moment you should see a "zoom" icon in the lower right portion of the map. Click on the zoom icon to see the map at its full size. Scroll around on the map to investigate the detailed information portrayed on it.

For more information on the history, development and creation process, click here to go to the USGS "Topographic Mapping" web site.

SCALE:

This USGS topographic map is a large scale map, meaning that on the surface of Earth, it represents a fairly small area. The opposite of a large scale map is a small scale map, which covers a large area such as the entire world. These are called relative scales.

The exact scale of this map is 1:24,000 which means that one inch on the map equals 24,000 inches on the ground or 2000 feet. The scale is unit independent so it may also mean one centimeter on the map equals 24,000 centimeters or 240 meters.

SYMBOLOGY:

Features on the surface of Earth are represented on a topo map, as well as other maps, as points, lines or area features; the designation of which is dependent on scale. For 7.5 minute topo quads, features such as churches, schools, small buildings and spot elevations are represented by point features. Roads, pipelines, fencelines, and streams are represented by line features. Urban areas, vegetative areas, lakes and ponds are represented as areal features.

In addition, different colors represent different types of information. For example:

• Green - vegetation
• Blue - water
• Purple - updated information
• Pink - built-up (urban) areas
• Brown - topographic contours
• Red - land division system grids
• Black - transportation and buildings

For more information on topograhic map symbols, visit the USGS Topographic Map Symbols web site.

For more information on topographic maps, visit geography.about.com/cs/topographicmaps/

Now that you have read the "Overview", go to the "Terminology" section.