Wednesday, October 5, 2011

Do you search for USGS or NGS Benchmarks?

One thing that always excites me when I get to the summit of a mountain is finding a Benchmark. I’m not really sure why, but those small, metal disks are fun to find. Maybe it’s because it represents a piece of history on the mountain. In most cases, they were installed by a previous generation, and will be there for many future generations to come. I decided to do a little research on the subject of them and this is what I have found.

 USGS Benchmark on the summit of Mount Liberty

Apparently, these Benchmarks could have been installed by one of two agencies; either the United States Geological Survey (USGS) or the National Geodetic Survey (NGS), formally the US Coast & Geodetic Survey. I would say the USGS Benchmarks are probably the most common, but I have found some older US Coast & Geodetic Survey Benchmarks as well. I have never found one with the newer, National Geodetic Survey name on it.


NGS Benchmark and Reference Mark on Mount Lafayette

One of the main jobs of the USGS, with respect to Benchmarking, is topographical mapping. They install these USGS Benchmarks to create an accurate reference point or location (including elevation) that can be revisited in the future. On the other hand, the NGS (if I understand the information I found correctly) determines proper elevations, shore and boundary lines, etc. Both departments use and update Benchmarks as needed for their respective functions.

NGS Benchmark on Stratham Hill

Now, a Benchmark could be anything really. It could be a pipe, a rock, a carving in a rock, but we commonly see them on mountain tops in the form of a small, metal disk. The disk usually has the department name that placed it there, the Benchmark’s name (typically, the mountain’s name) and the elevation the disk is placed at. In some cases, the disk isn’t at the true summit or highest point on the mountain. The surveyor will place it in a location that he can point the best line to other peaks or locations for his mapping purposes. Therefore, some summit top Benchmarks may have a lower elevation callout than the actual summit elevation. Most Benchmarks will have a triangle or cross on it, which is a sure sign that it is a true Benchmark. However, there are other disks kicking around these summits that aren’t actually Benchmarks! Don't let them fool you!

 USGS Benchmark and Reference Mark on Mount Pierce

Some Benchmarks are placed along with Reference Marks. In most cases, there are Reference Marks (commonly in numbers of two or more) placed near the Benchmark with a specific direction and distance to help reset or triangulate the Benchmark location if ever needed in the future. These Reference Marks look just like Benchmarks, but have an arrow in the center and are usually marked with “Reference Mark”. I have definitely found a few of these in my travels and thought the mountain either had more than one Benchmark or I apparently didn’t find the true Benchmark, only taking a photo of the Reference Mark. Fool me once...right! There are also Azimuth Marks (directing true direction) and Cadastral Marks (denoting land boundaries) which are used from time to time and look just like a Benchmark. I have never come across either of these types of disks in my travels.

 USGS Benchmark and my boot on Mount Washington!

Currently, there is no way of knowing how many Benchmarks have been placed around the United States. It is thought that there is over one million currently placed in various locations, but there is no true record. You can obtain NGS Benchmark datasheets, which contain a lot of information regarding specific Benchmarks, on their website: http://www.ngs.noaa.gov/cgi-bin/datasheet.prl. As for USGS Benchmarks, information regarding specific ones cannot be found online and you must inquire with USGS personnel to acquire information.

 USGS Reference Mark on Iron Mountain...I missed the Benchmark

So, which mountains have I been lucky enough to find these Benchmarks and which ones have I missed? I’m sure you’ve already noticed the photos in this post which have a lot of these peaks mentioned. I’ve found USGS or NGS Benchmarks on Mount Washington, Mount Pierce, Mount Lafayette, Mount Liberty and Stratham Hill. I have found USGS or NGS Reference Marks on Mount Pierce, Mount Lafayette and Iron Mountain. However, I thought at the time, the Reference Mark on Iron Mountain was in fact the Benchmark. So, I never actually found the Benchmark on this mountain which means I will need to revisit it and find it. I know, after reading and viewing other trip reports, I have missed Benchmarks on Mount Osceola, Mount Major, Mount Cardigan, Mount Chocorua and probably many more. I do my best to make a point to look for these Benchmarks as sometimes they are a bit hidden or people are perched on them eating lunch. I also know, now, that a Reference Mark means a Benchmark is close by.

Left, Sandwich Wilderness Bound Mark on Mount Potash
Right, Property Bound at the base of the Pasture Path up to Mount Katherine
These may be considered Cadastral Marks, although I'm not sure

Hopefully, this was informative for you and somewhat interesting. For me, well I love this stuff. Anything that may carry any ounce of history or significance, such as a USGS or NGS Benchmark, is always intriguing to me. I’ll continue to search them out and I hope you do too!

A lot of the research I did and information I found to write this post was found on SummitPost.org. For a more detailed information on the history of Benchmarks, visit: http://www.summitpost.org/on-bench-marks-history-purpose-and-a-mountaineer-s-perspective/613557



  1. YES! I love finding the Benchmarks, my favorite is Mt. Washington! I got a coin this year when I hiked up of the Benchmark. :)

  2. Yes, very cool. Mts. Isolation and Moriah have several reference marks triangulating the benchmark. Neat stuff to know!

  3. Karl . . . excellent topic for a Blog report + an informative and first-rate narrative. A winning combination!!


  4. Yes - I like looking for them too. I immediately thought of the ones on Moriah, and as Dan reminded us, there's some on Isolation, too. There is one on Carrigain, and I think I saw one on Carter Dome, too.

  5. It looks like you overcame writers block with an awesome post! I saw something that looked like a benchmark posted near the remains of an old rail bridge in the Lincoln Brook Trail on my way out from the Owl's Head attempt. This was nowhere near the summit of a mountain, I wish I had taken a photo of it. I agree with you that anything related to history is awesome!

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  7. Benchmarking is pretty cool. It's always fun to find them even when they aren't on top of a summit. We've found a few like that and some that aren't even from USGS or NGS. We've seen some around these parts from TVA. If you've ever done geocaching, then you might also find that they have a way for you to claim benchmarks you've found. It's been forever since we've done any geocaching, and the last time I tried to claim a benchmark, the one we found wasn't in their database so I'm not sure how up to date they are these days. Anyway here's a link in case you are interested: http://www.geocaching.com/mark/default.aspx
    Great post as always.

  8. Hi Ariel - I agree. I love the MW one. It's strange how it has a pin in the middle of it, unlike others I have seen. I have the small key chain benchmark!

    Hi Dan and Meena - I hope to check out Isolation and Moriah someday to check them out. Most likely, I'll get to Moriah before Isolation, due to difficulty. Do you have any pics of these? If so, share them on the LFAHNH Facebook Page.

    Hi John - Thanks very much for the kind words!

    Hi Summerset - Carrigain and Carter Dome are two peaks I'll need to check out sooner than later. I'll definitely check out the Benchmarks if I get up there!

    Hi Grant - Thanks! Those old ones are definitely cool. It probably was a Benchmark as they don't have to be on mountain tops. Never go by one without snapping a photo! I hope you learned your lesson! Just kidding!

    Hi Tim - I've checked out this geocaching database before. I really want to get into it, but like everything else, time hinders me. My GPS unit is still brand new, sitting in the box...no idea how to use it!!! I hope I can start geocaching at some point. A lot of my friends do it. Thanks for sharing the info.

    Thanks everyone,

  9. I saw one on Moosilauke today and got a photo, and then remembered I got a photo of the one on Cadillac Mt. in Acadia NP in Maine, too.