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Maps

Map Scales

Maps are always smaller than the area they show. The scale of a map is the actual reduction factor needed to depict an area on a map that size. Scale is an important factor in helping you decide whether a map will show in enough detail the features you need.

Scale can be expressed either in words, such as "one inch equals 3 miles" or as a relative fraction, expressed as a ratio. An example would be 1:250,000 which could also be expressed verbally as "one unit (such as an inch) on the map equals 250,000 units (such as inches) on the earth".

The phrases smaller scale and larger scale are often misunderstood.

The smaller the number to the right of the colon in the ratio, the larger the scale.
EXAMPLE: 1:63,000 is a larger scale map than 1:250,000

The larger the scale, the smaller the area being depicted, and the greater the amount of detail being shown. One of the largest scale sets, and thus the most detailed, that the Cofrin Library owns are the USGS 7.5 minute topographic maps, which are at a scale of 1:24,000.

Since scale deals with not just linear measurements, but area, the differences in the amount of area covered by various scales can also be confusing.

EXAMPLE: If you have two maps of the same size, one at a scale of 1:100,000 will cover four times as much area as one at a scale of 1:50,000.

More Tips

  • Many maps come in sets composed of numerous individual sheets.  The catalog record will list the set, but not necessarily the sheets in the set.  A set will usually have an index map for you to consult to pick out the sheet you need.
  • Each sheet in a set generally lists the names of the sheets surrounding it in the outside border, to help you quickly move around without going back to the index sheet.
  • Use the latitude and longitude given in a gazetteer to find a location on a sheet.   Even if the map scale does not allowing the names of smaller places to appear on the map, you can still pinpoint it on the sheet with these coordinates.
  • Maps generally do not circulate unless needed for a class presentation.  This is because they are fragile and it is difficult to transport them without damaging them.  In some cases, our agreement with the issuing agency stipulates that they may not circulate.

Gazetteers

A gazetteer can help you locate a city, region, country, or geographic feature even if you are not sure where it is. A gazetteer will give you the latitude and longitude or a verbal description so that you may locate a place on any map of that area. In addition, some gazetteers are designed to work with a specific atlas or set of maps, and will be keyed to that.  Some gazetteers will give you the geographic coordinates, or latitude and longitude of a place so you can place it on any map of the area, even if the map scale does not display places to the detail needed. Some of the gazetteers the library owns include: