![]() Concentric circles of hachured contour lines indicate a closed depression. Instead, these lines are continuous, although they can continue off the edge of the map. Concentric circles of contour lines indicate a hilltop or mountain peak. In addition to obeying the set contour interval for a map, contour lines should never branch (split) or simply end inside of the mapped region. Benchmark locations will normally be found in the area between contour lines. For example, a benchmark of 236ft will be found somewhere between the 230ft and 240ft contour line (if the contour interval is 10ft), or between the 235ft and 240ft contour line (if the contour interval is 5ft). These benchmarks are rarely located on a contour line and instead are usually identified by a black “x” or identified with the letters “BM” and with the elevations included in black numbers (as opposed to the brown numbers on index contours). These surveyed points are exact elevations above sea level and are commonly used to mark the elevations of mountains, hilltops, road intersections, and airport runways. The process of devising a set of marks of appropriate size, color, shape, and pattern, and assigning them to map features to convey their. In addition to contour lines, topographic maps will also have benchmarks (actual surveyed points) in various locations on your map. symbology The process of devising a set of marks of appropriate size, color, shape, and pattern, and assigning them to map features to convey their characteristics at a given map scale. Closed depressions formed by natural processes need not be karst in origin to represent a source of focused-recharge. The map representation applies to closed depressions of both natural and anthropogenic origin. Remember to use the contour lines to determine the elevations, and the bar scale on your map to measure the distance. On a topographic map a closed depression is typically represented by a hachured contour line forming a closed loop.
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