Many readers have probably visited mountaintops and seen a metal disc-shaped benchmark that was cemented in place at or near the highest point. Across the continental U.S. (as well as in Alaska and Hawaii) there are survey benchmarks set in rock or permanent structures that range from city sidewalks and bridges to remote ridges and mountaintops. These have been set by surveyors since 1879.
Searching for benchmarks can be an great way to enjoy the outdoors. You can customize this activity to fit your available time, energy, and skills. For example, some benchmarks are easily accessible by driving your car, parking and then walking just a short distance. Whereas to locate other benchmarks, you might need to hike a trail for several miles. And, in some cases, you might need to use your map and compass skills to bushwhack through the woods in your attempt to locate a benchmark.
As a hiker, I can see similarities between searching for an old logging camp, and searching for benchmarks in remote locations. However, there are some who consider "benchmarking" as just another form of geocaching. Regardless, if you are outdoors having fun by searching for an old logging camp, or a benchmark, or whatever, does it really matter if you're classified as a hiker, or a geocacher?
Should you decide to try your hand at locating benchmarks, you should be aware that benchmarks are placed by two separate governmental agencies, as follows.
_ The National Geodetic Survey (NGS) was formerly known as the Coast and Geodetic Survey. It is part of NOAA (National Oceanic and Atmospheric Administration) which is under the Department of Commerce. It is concerned with the maintenance of the National Spatial Data Infrastructure.
_ The US Geological Survey(USGS) is under the Department of the Interior. This agency is responsible for the production of topographic maps.
Shown in the photo below are two benchmarks. The one on the left was placed by the USGS. The one on the right was placed by the NGS.
|Benchmark examples: USGS benchmark on left; NGS benchmark on right|
It was interesting to discover that benchmarks placed by NGS have an online searchable database (click HERE). There's a slight learning curve to using this database, but if you should decide to go on a hunt for benchmarks, it's worth taking the time to master this resource.
As for USGS survey benchmark data, unfortunately that agency has not yet put their paper records of benchmark locations into computerized files. However, some USGS benchmark locations have found their way into the NGS database. But for USGS benchmarks that are not in the NGS database, it can be challenging to find them without contacting the USGS directly by phone or e-mail. (For Eastern U.S., call 573-308-3500, or e-mail at firstname.lastname@example.org; for Western U.S. call 303-202-4400, or e-mail at email@example.com.)
And so, with all that background information out of the way, I'll now turn to the topic of this report which pertains to locating survey benchmarks in the area of Bethlehem, NH. I'll begin by saying that very little searching is required to locate a benchmark located atop Bethlehem's Mt. Agassiz, which can be accessed by a 0.7 mile trek up a private roadway where the landowner generously allows hiker traffic.
However, there are other benchmarks in the Bethlehem area which require a bit of searching. Shown below are photos of just a couple of these more obscure benchmarks.
The NGS benchmark seen below was located in the vicinity of Pierce Bridge. The left panel shows a close-up image of the benchmark. The right panel shows the boulder in the woods where the benchmark has resided since 1933!
|NGS Benchmark located in vicinity of Pierce Bridge, NH|
A USGS benchmark was located near Wing Road (Bethlehem). It was embedded on top of an old dam near an abandoned section of the old Boston & Maine Railroad track.
In the photo below, the left panel shows a close-up image of the Wing Road benchmark. The right panel shows the top of the old dam where the benchmark has resided since 1925! However, it appears that its patina has been polished away. (Perhaps it would be better to simply remove any surface debris and leave the patina intact?)
|USGS Benchmark located near Wing Road in Bethlehem, NH|
The Wing Road benchmark is a good example of some of the side benefits of "benchmarking". This search took me to a lovely setting near a pond which was adjacent to an abandoned railroad track. Had I not been out there looking for a benchmark, I might never have had the pleasure of exploring this particular location.
|Pond located near the Wing Road benchmark|
|Abandoned railroad track near the Wing Road benchmark|
To sum it up, I'm looking forward to occasionally pairing a "benchmarking" adventure with one of my other outdoor activities of hiking, mountain-biking, cross-country skiing, snowshoeing. This seems like a combination that could work well, and add some extra spice to those pursuits.