The ability to read and use a variety of maps is crucial in land surveying. Land surveyors begin with a large-scale map in order to make a landscape-level plan. After the land surveyor determines the need for specific projects a stand-level map will be required.
Two kinds of stand-level maps include: Transportation maps and Topographic maps.
Types of Maps
Transportation maps usually cover a large area (ex. an entire county or state). It can also act as a stand-level tool to locate areas where project work takes place. Transportation maps vary in design depending on where it is being used. For example, Forest Service maps usually concentrate on roads within National Forest lands and exclude other outside connecting roads. The Bureau of Land Management (BLM) does the same for BLM lands. Though this may be useful for the Forest Service and BLM, it can often create problems due to the inconsistency for land surveyors working in an area with multiple ownerships.
Topographic Maps (topo maps for short) are maps that provide extensive close-up details including relief, hydrology, vegetations and human-made structures. In the United States the U.S. Geological Survey (USGS) is responsible for creating topographic mapping. Over 54,000 quadrangles (map sheets) cover every inch of the United States. The USGS’ mapping scale for topo maps is 1:24,000. This indicates that one inch of the map is equal to 24,000 inches on the ground or 2,000 feet. Each quadrangle is called 7.5 minute quadrangles because they cover an area of 7.5 minutes longitude high by 7.5 minutes longitude wide. Topo maps are among the most valuable type of maps for the public and government.
Map Scales and Distances
Accurate distances on maps are only measured if a map is drawn with a scale. Map scales are usually written in the form of a ratio (1:12,000) or in the form of a representation (1 inch = 1 mile). In the form of a ratio, 1 inch equals 12,000 inches (1,000 feet) on the ground. In the form of a representation 1 inch shown on the map is equal to 1 mile on the ground. In both cases you are able to find a ground distance between two points on the map by using a ruler to measure and multiplying by the appropriate map scale.
Map Symbols
Since maps are a smaller representation of the world at large, map symbols are often used to represent real objects. Maps simply would not exist without the use of symbols. Symbols can be displayed on maps both through shapes and colors. A small circle can depict a point of interest, brown circles indicating recreational sites, green circles indicating rest stops, and red circles indicating services. Colors are also applied in larger areas on maps such as green indicating forested land and blue indicating waterways. Map legends are often included on maps to ensure proper interpretation of all the symbols and colors used on a map.
The U.S. Public Land Survey System (PLSS) has a wide variety of symbols used for land survey systems. Land survey system symbols include Township lines, Range lines, Section lines, Found section corners, Found closing corners, Witness corners, Meander corners, Land grants, Mining claims, Monuments, and Fence lines.
Thoughts