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Benchmarking, also known as benchmark hunting, [1] is a hobby activity in which participants find benchmarks (also known as survey markers or geodetic control points). The term "benchmark" is used only to refer to survey markers that designate a certain elevation , but hobbyists often use the term benchmarks to include triangulation stations or ...
The height of a benchmark is calculated relative to the heights of nearby benchmarks in a network extending from a fundamental benchmark. A fundamental benchmark is a point with a precisely known relationship to the vertical datum of the area, typically mean sea level. The position and height of each benchmark are shown on large-scale maps.
NGVD29 was superseded by the North American Vertical Datum of 1988 , [3] based upon reference to a single benchmark (referenced to the new International Great Lakes Datum of 1985 local mean sea level height value), although many cities and U.S. Army Corps of Engineers "legacy" projects with established data continued to use the older datum. [4]
Survey markers, also called survey marks, survey monuments, or geodetic marks, are objects placed to mark key survey points on the Earth's surface. They are used in geodetic and land surveying . A benchmark is a type of survey marker that indicates elevation ( vertical position ).
Some of Illinois’ neighbors fared well in Clever’s survey, including Kentucky at No. 8 and Missouri at No. 10. According to the survey, the top five states to live in are North Carolina ...
It traces its history to the Survey of the Coast, which was formed in 1807 as the first scientific agency of the U.S. federal government. It became the United States Coast Survey in 1836 and the United States Coast and Geodetic Survey in 1878, the latter name change reflecting the increasing role of geodesy in its work. Upon the creation of ...
Figure 1. This BLM map depicts the principal meridians and baselines used for surveying states (colored) in the PLSS. The following are the principal and guide meridians and base lines of the United States, with the year established and a brief summary of what areas' land surveys are based on each.
Each of these maps covers an area bounded by two lines of latitude and two lines of longitude spaced 7.5 minutes apart. Nearly 57,000 individual maps in this series cover the 48 contiguous states, Hawaii, U.S. territories, and areas of Alaska near Anchorage, Fairbanks, and Prudhoe Bay. The area covered by each map varies with the latitude of ...