澳门六合彩历史记录

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Topographic Maps

Photo of a topigraphic map with a geometry compass resting on top of it.

Topographic maps show relief (landforms) using contours, lines of equal elevation, as well as cultural features (roads, railroads, buildings and developed areas), and physical features (water bodies and landforms). The US Geological Survey (USGS) has published topographic maps for every state and territory since 1884. U.S. topographic maps are produced at various scales (scale is the relationship between the distance on the map to the distance on the ground, usually shown as a fraction [1:24,000] or described (1 inch to a mile). Early U.S. topographic maps were produced at a scale of 1:125,000 (approximately 1 inch to 2 miles) or 1:62,500 (approximately 1 inch to 1 mile). The USGS now produces large-scale topographic maps at a scale of 1:24,000, which covers an area 7.5" X 7.5" (one-eighth of a degree square). The Survey also produces intermediate-scale topographic at scales of 1:100,000 and 1:250,000 that cover 30' X 60' (one half of a degree by 1 degree) and 1 degree X 2 degrees, respectively. Some topographic maps show vegetated areas as well.

For more information on USGS topographic maps and topographic map symbols, consult the following USGS' web sites:

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Finding Topographic Maps

The 澳门六合彩历史记录 Libraries have topographic maps for every U.S. State and territory in the Map Collection on the 4th Floor of Malpass Library. They are filed by state and quadrangle name. USGS topographic maps for a particular area can be identified using paper, graphical indexes, available in these libraries, or by using the . To find the name of a topographic map containing a feature, enter the place name of interest in the Feature Name field and select the state with the pull-down menu. A list containing one or more places will appear. Select the place of interest from the list to see the full record for that location.

Current U.S. Topographic maps can only be viewed online at the National Map web site. To view a map for a particular area, click on on the left hand side of the page. On the Map Store page, enter a place name in the search box to view the maps available for that area.

The can be used to create a map interactively. Users can zoom into an area of interest and specify the information to be displayed on the map. The map data can then be downloaded and used in a Geographic Information System . For assistance using GIS, ask for help at the Government Information Reference Office, 4th Floor, Malpass Library.