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How Browse USGS By Category and Location WorksThe USGS Thesaurus defines a high-level, tree-like hierarchy of categories that describe the science and products of USGS. This feature lets you move around the "tree" of the Thesaurus to explore the categories -- their definitions, how they're used, broader or narrower terms, etc. -- and find selected USGS web pages that contain more infomation about a category. Since most USGS information is spatial, the browse also lets you specify an area and selects USGS web pages that best fit that area.
Where to StartYou can start browsing right at the top of the "tree" to see the structure of the Thesaurus. Or, you may prefer to start with the Alphabetical Index of USGS Science Categories. The CollectionThe list of USGS Web pages with more information on categories comes from a collection of approximately 2,100 key USGS Web pages (out of more than 300,000 in over 300 USGS Web sites) selected by librarians, webmasters, and subject-matter experts to support the terms of the USGS Thesaurus. These pages are carefully cataloged by category and location. "Browse USGS by Category and Location" is intended to help you find the most relevant links to the more general USGS topics. If you're looking for something very specific, you may find the USGS Search Engine (also accessed from the USGS home page) more effective. Spatial SearchThe spatial selection routine uses the bounding latitudes and longitudes of the area you select to find Web pages that best fit the selected area. Hence, if you select "Illinois," the selector will give the greatest preference to web pages about the State of Illinois, and lesser preference to web pages about Chicago (too small) or the United States (too big). A big advantage of a spatial search based on latitude and longitude is that it doesn't depend on the complex relationships associated with names. Hence, a page about Chicago probably would be found when searching for "Cook County, Illinois" because their boundaries are similar. The best-fit ranking method keeps national reports from dominating the search. As you might expect, USGS has a lot of pages about the United States. When looking for pages about Illinois, the best fit would be for reports specifically about Illinois. Since the bounds of Illinois are much smaller than the bounds of the United States, the national reports are ranked low. A report about the Illinois-Indiana region, however, would rank higher than one about the United States, but lower than one about Illinois. The procedure works the opposite way too: a search of "United States" would give lower rankings to local and regional reports. To allow it to operate quickly, the spatial search is based on a bounding rectangle, not the detailed boundaries of the selected place. This works great for rectangular Colorado, and less well for, say, Massachusetts! The oddities that result tend to receive lower rankings. Nevertheless, it's not unusual to see some strange results down in the bottom of the list. |
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U.S. Department of the Interior | U.S. Geological Survey URL: http://answers.usgs.gov/feature_gsbrowse.htm Contact: Contact USGS Last modified: |