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  • 1. Topographic Map SymbolsWhat is a Topographic Map? Reading Topographic MapsA map is a representation of the Earth,or part of it. The distinctive character- Interpreting the colored lines, areas, and other symbols is the firstistic of a topographic map is that the step in using topographic maps. Features are shown as points, lines,shape of the Earth’s surface is shown or areas, depending on their size and extent. For example, individualby contour lines. Contours are imag- houses may be shown as small black squares. For larger buildings,inary lines that join points of equal the actual shapes are mapped. In densely built-up areas, most indi-elevation on the surface of the land vidual buildings are omitted and an area tint is shown. On someabove or below a reference surface, maps, post offices, churches, city halls, and other landmark buildingssuch as mean sea level. Contours are shown within the tinted area.make it possible to measure the The first features usually noticed on a topographic map are theheight of mountains, depths of area features, such as vegetation (green), water (blue), and denselythe ocean bottom, and steep- built-up areas (gray or red).ness of slopes. Many features are shown by lines that may be straight, curved,A topographic map shows solid, dashed, dotted, or in any combination. The colors of the linesmore than contours. The usually indicate similar classes of information: topographic contoursmap includes symbols (brown); lakes, streams, irrigation ditches, and other hydrographicthat represent such fea- features (blue); land grids and important roads (red); and other roads and trails, railroads, boundaries, and other cultural features (black).tures as streets, buildings, At one time, purple was used as a revision color to show all featurestreams, and vegetation. changes. Currently, purple is not used in our revision program, butThese symbols are con- purple features are still present on many existing maps.stantly refined to betterrelate to the features they Various point symbols are used to depict features such as buildings,represent, improve the campgrounds, springs, water tanks, mines, survey control points,appearance or readability of and wells. Names of places and features are shown in a color cor-the map, or reduce production responding to the type of feature. Many features are identified bycost. labels, such as “Substation” or “Golf Course.” Topographic contours are shown in brown by lines of differentConsequently, within the same widths. Each contour is a line of equal elevation; therefore, contoursseries, maps may have slightly dif- never cross. They show the general shape of the terrain. To helpferent symbols for the same feature. the user determine elevations, index contours are wider. ElevationExamples of symbols that have values are printed in several places along these lines. The narrowerchanged include built-up areas, roads, intermediate and supplementary contours found between the indexintermittent drainage, and some letter- contours help to show more details of the land surface shape. Con-ing styles. On one type of large-scale tours that are very close together represent steep slopes. Widelytopographic map, called provisional, spaced contours or an absence of contours means that the ground slope is relatively level. The elevation difference between adjacentsome symbols and lettering are hand- contour lines, called the contour interval, is selected to best showdrawn. the general shape of the terrain. A map of a relatively flat area may have a contour interval of 10 feet or less. Maps in mountainous areas may have contour intervals of 100 feet or more. The contour interval is printed in the margin of each U.S. Geological Survey (USGS) map. Bathymetric contours are shown in blue or black, depending on their location. They show the shape and slope of the ocean bottom surface. The bathymetric contour interval may vary on each map and is explained in the map margin. U.S. Department of the Interior U.S. Geological Survey
  • 2. BATHYMETRIC FEATURES COASTAL FEATURES Area exposed at mean low tide; sounding Foreshore flat datum line*** Channel*** Coral or rock reef Sunken rock*** Rock, bare or awash; dangerousBOUNDARIES to navigation National Group of rocks, bare or awash State or territorial Exposed wreck County or equivalent Depth curve; sounding 18 Civil township or equivalent 23 Incorporated city or equivalent Breakwater, pier, jetty, or wharf Federally administered park, Seawall reservation, or monument (external) Federally administered park, Oil or gas well; platform reservation, or monument (internal) CONTOURS State forest, park, reservation, or Topographic monument and large county park Index 6000 Forest Service administrative area* Forest Service ranger district* Approximate or indefinite National Forest System land status, Intermediate Forest Service lands* Approximate or indefinite National Forest System land status, non-Forest Service lands* Supplementary Small park (county or city) DepressionBUILDINGS AND RELATED FEATURES Building Cut School; house of worship Athletic field Fill Built-up area Continental divide Bathymetric Forest headquarters* Index*** Ranger district office* Intermediate*** Guard station or work center* Index primary*** Racetrack or raceway Primary*** Airport, paved landing strip, runway, taxiway, or apron Supplementary*** CONTROL DATA AND MONUMENTS Unpaved landing strip Principal point** Well (other than water), windmill or wind generator U.S. mineral or location monument USMM 438 Mile Tanks River mileage marker 69 Covered reservoir Boundary monument Third-order or better elevation, BM Gaging station with tablet 9134 Located or landmark object (feature as labeled) Third-order or better elevation, 5628 recoverable mark, no tablet Boat ramp or boat access* With number and elevation 67 4567 Roadside park or rest area Horizontal control Third-order or better, permanent mark Neace Picnic area With third-order or better elevation BM 52 Campground With checked spot elevation 1012 Winter recreation area* Coincident with found section corner Cactus Cemetery Cem Unmonumented**
  • 3. CONTROL DATA AND MONUMENTS – continued PROJECTION AND GRIDSVertical control Neatline 39˚15’ Third-order or better elevation, with tablet BM 5280 90˚37’30” Third-order or better elevation, Graticule tick 55’ 528 recoverable mark, no tablet Graticule intersection Bench mark coincident with found BM section corner 5280 Datum shift tick Spot elevation 7523 State plane coordinate systemsGLACIERS AND PERMANENT SNOWFIELDS Primary zone tick 640 000 FEET Contours and limits Secondary zone tick 247 500 METERS Tertiary zone tick 260 000 FEET Formlines Quaternary zone tick 98 500 METERS Glacial advance Quintary zone tick 320 000 FEET Glacial retreat Universal transverse metcator gridLAND SURVEYS UTM grid (full grid) 273Public land survey system Range or Township line UTM grid ticks* 269 Location approximate RAILROADS AND RELATED FEATURES Location doubtful Standard guage railroad, single track Protracted Standard guage railroad, multiple track Protracted (AK 1:63,360-scale) Narrow guage railroad, single track Range or Township labels R1E T2N R3W T4S Narrow guage railroad, multiple track Section line Location approximate Railroad siding Location doubtful Railroad in highway Protracted Railroad in road Railroad in light duty road* Protracted (AK 1:63,360-scale) Section numbers 1 - 36 1 - 36 Railroad underpass; overpass Found section corner Railroad bridge; drawbridge Found closing corner Railroad tunnel WC Witness corner Railroad yard Meander corner MC Weak corner* Railroad turntable; roundhouseOther land surveys RIVERS, LAKES, AND CANALS Range or Township line Perennial stream Section line Perennial riverLand grant, mining claim, donation land Intermittent streamclaim, or tractLand grant, homestead, mineral, or Intermittent riverother special survey monumentFence or field lines Disappearing streamMARINE SHORELINES Falls, small Shoreline Apparent (edge of vegetation)*** Falls, large Indefinite or unsurveyed Rapids, smallMINES AND CAVES Rapids, large Quarry or open pit mine Gravel, sand, clay, or borrow pit Mine tunnel or cave entrance Masonry dam Mine shaft Prospect Tailings Dam with lock Mine dump Former disposal site or mine Dam carrying road
  • 4. RIVERS, LAKES, AND CANALS – continued SUBMERGED AREAS AND BOGS Perennial lake/pond Marsh or swamp Intermittent lake/pond Submerged marsh or swamp Dry lake/pond Wooded marsh or swamp Narrow wash Submerged wooded marsh or swamp Wide wash Canal, flume, or aqueduct with lock Elevated aqueduct, flume, or conduit Land subject to inundation Aqueduct tunnel Water well, geyser, fumarole, or mud pot Spring or seep SURFACE FEATURESROADS AND RELATED FEATURESPlease note: Roads on Provisional-edition maps are not classified Leveeas primary, secondary, or light duty. These roads are all classified asimproved roads and are symbolized the same as light duty roads. Sand or mud Primary highway Disturbed surface Secondary highway Light duty road Gravel beach or glacial moraine Light duty road, paved* Light duty road, gravel* Light duty road, dirt* Tailings pond Light duty road, unspecified* TRANSMISSION LINES AND PIPELINES Unimproved road Unimproved road* Power transmission line; 4WD road pole; tower 4WD road* Telephone line Trail Aboveground pipeline Highway or road with median strip Underground pipeline Highway or road under construction VEGETATION Highway or road underpass; overpass Woodland Highway or road bridge; drawbridge Shrubland Highway or road tunnel Orchard Road block, berm, or barrier* Vineyard Gate on road* T Mangrove Trailhead* H * USGS-USDA Forest Service Single-Edition ** Provisional-Edition maps only. Quadrangle maps only. Provisional-edition maps were established to expedite In August 1993, the U.S. Geological Survey and the completion of the remaining large-scale topographic U.S. Department of Agriculture’s Forest Service signed quadrangles of the conterminous United States. They an Interagency Agreement to begin a single-edition contain essentially the same level of information as the joint mapping program. This agreement established the standard series maps. This series can be easily recognized coordination for producing and maintaining single-edition by the title “Provisional Edition” in the lower right-hand primary series topographic maps for quadrangles containing corner. National Forest System lands. The joint mapping program eliminates duplication of effort by the agencies and results in a more frequent revision cycle for quadrangles containing *** Topographic Bathymetric maps only. National Forests. Maps are revised on the basis of jointly developed standards and contain normal features mapped by the USGS, as well as additional features required for effi- Topographic Map Information cient management of National Forest System lands. Single- For more information about topographic maps edition maps look slightly different but meet the content, produced by the USGS, please call: accuracy, and quality criteria of other USGS products. 1-888-ASK-USGS or visit us at http://ask.usgs.gov/ Printed on recycled paper