What is a benchmark?
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 churchspire,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 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).
The interesting thing about benchmarks is that a majority of them are located in plain sight (though largely ignored by the general public). Searching out these locations and documenting them allows others to share pictures of the various areas where they are placed. There's a certain excitement to be the first to find and document a control point, as well as seeing what others have found through photos on the website's benchmark gallery. Some of these points haven't been visited and documented in a very long time,so you may also be rediscovering long neglected objects of American history as well!
A GPSr makes getting to the right area easier, but when you're there, you will (generally) be better off if you use the details of the benchmark's location description to locate it. Because most of these benchmarks were installed prior to the existence of GPS,the benchmark database is geared toward finding benchmarks from the descriptions, not the coordinates. Occasionally, however, a good GPSr will prove to be an invaluable tool in finding a benchmark, especially in situations where the location's description is inaccurate due to development and the passage of time. A good GPSr will also help you get to benchmarks in locations you are unfamiliar with.
This series of caches has been established to introduce cachers to the world of benchmarking. Somewhere near each cache in the series is a benchmark. The benchmark can be logged on geocaching.com.
This cache will bring you to the town of Hatfield. You are looking for a magnetic nano with log a log only so bring your own writing instrument and a set of tweezers. After logging the cache project a waypoint that is 254 feet away at a heading of 290 degrees. The waypoint will take you to a small field that contains 3 loggable benchmarks.