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Maps With Borders vs. Seamless Maps:
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USGS Quadrangles (7½ Minute Topographic Maps) include the
map image, and borders (map collars) that surround each map image.
Maps that have their collars clipped are called 'seamless' maps. Maps that include the original borders are called 'collared' maps. The black line that separates the map image and the map collar information is called the 'neat line'. Many digital mapping solutions offer products with 'seamless maps'. At first glance these products may appear to be more convenient than maps with collars (or borders), but they do have very serious shortcomings. The supplementary information included in the collars is as important as the the map image. If you plan to use seamless digital topographic maps for filing real estate, mining, mineral or petroleum claims and reports, make certain that a seamless map is acceptable. Many filings require standard quadrangles. In addition, many seamless maps are considered 'new works' and copyrighted, they are not suitable for distribution or professional use. All iGage Mapping Corporation products include the map collars. All Topo Maps 1:24,000 scale and 1:63,360 (Alaskan) quadrangles can be converted on demand to seamless map stock using the included BigTopo [ see BigTopo Tour ] tool, but the collars are by default available and shown in the viewer. |
| PLS (Public Land System) Township, Range and Section markings are found on the collars of released maps. It is not possible to determine the Township and Range of the sections shown on the seamless map (left) below. The collared map (right) clearly indicates township and range markings. |
Seamless Map
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Collared Map (with borders)
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Contour IntervalQuadrangles are produced with different contour intervals. Contour intervals are indicated in collar notations under the map's scale:
Different maps have different contour intervals, and some quadrangles are split into two or more contour regions. Lat/Lon, UTM, State Plane Grid TicksA variety of tick marks and annotations are made in the collars. Quadrangles are produced in both NAD27 and NAD83 datums, with a variety of projections and ellipsoids. This information is always noted in the sheet collars and is removed when the maps are seamed. Lat/Lon Corner Ticks in both NAD27 (map corner) and NAD83 (dashed ticks):UTM and State Plane Grid TicksPaper Map Name, State and County Coverage Map Name, State and County. Without the USGS quadrangle name you may have a difficult time using a seamed product to select paper maps for purchase. Projection, Datum, Source and Supplementary Tick Information |
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