Скачать или смотреть Benchmark Hunting at Cypress Creek Preserve

I have found several of these benchmarks out hiking. This one had a date of 1988 on it. Not sure if it was placed here here then or not because there is another date on it as well. A benchmark is a point whose position is known to a high degree of accuracy and is normally marked in some way. The marker is often a metal disk made for this purpose, but it can also be a church spire, a radio tower, a mark chiseled into stone, or a metal rod driven into the ground. Over two centuries or so, many other objects of greater or lesser permanence have been used. Benchmarks can be found at various locations all over the United States. They are used by land surveyors, builders and engineers, map makers, and other professionals who need an accurate answer to the question, "Where?" Many of these markers are part of the geodetic control network (technically known as the National Spatial Reference System, or NSRS) created and maintained by NOAA's National Geodetic Survey (NGS).