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What do the colors on a topographic map mean?
The colors of the lines usually indicate similar classes of information: topographic contours (brown); lakes, streams, irrigation ditches, and other hydrographic features (blue); land grids and important roads (red); and other roads and trails, railroads, boundaries, and other cultural features (black).
How are inches represented on a topographic map?
Scale is represented in two different ways on a topographical map. The first is a ratio scale. The ratio scale on this map is 1:24,000. What it means is that one inch on the map represents 24,00 inches on the ground. Below the ratio scale is a graphic scale representing distance in miles, feet and meters.
How are valleys indicated on a topographic map?
Also know as gullies, drainages, ravines, and couloirs, valleys are indicated by “V“or ”U“ shaped contour lines that “point” uphill, toward higher elevation. Ridge: A landform with an elevated crest that slopes down on the sides. Ridges are also shown by “V“ or ”U“ shaped contours, but these “point” downhill, toward lower elevations.
Which is the reference point for a township line?
Township Lines: The east to west lines which mark township boundaries. Principal Meridian: The reference or beginning point for measuring east or west ranges. Map of meridians & base lines from the BLM web server
Where are the contour intervals on a topographic map?
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.
What do widely spaced contours on a map mean?
Widely spaced contours or an absence of contours means that the ground slope is relatively level. The elevation difference between adjacent contour lines, called the contour interval, is selected to best show the general shape of the terrain. A map of a relatively fl at area may have a contour interval of 10 feet or less.
Where are the bathymetric contours on a USGS map?
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.