Comments on: Survey Benchmark Monument Locations

By: Sheila

Sheila — Mon, 17 Nov 2025 19:17:34 +0000

In reply to Greg Mallon. Hi, I actually found one of these markers at a thrift store in northern Virginia not too long ago! Was doing research and came across your comment. Can’t find anything in these markers. I assumed they were mass produced as souvenirs but maybe not? Mine looks busted up as if it were an actual working marker.

By: Greg Mallon

Greg Mallon — Wed, 28 Jun 2023 01:47:11 +0000

Does anyone know if the Pentagon had any survey benchmarks? I once saw (in the 1990’s) a brass or bronze marker about 4” wide & it said “Pentagon Reservation Boundary” or something like that. I was also itself a 5 sided pentagon shape.
It was one single piece and on the bottom was a ROD (same material) extending perpendicularly downward (as an obvious marker formerly in the ground but sheered off).
I’ve often wondered if anyone knows where the “others” are and if there were 4 or 5 in total. I’ve never seen it written about anywhere.

By: Bobby Lacoste Stroud

Bobby Lacoste Stroud — Mon, 08 May 2023 08:19:13 +0000

Greetings,
Many, many years ago, a good friend of mine (now deceased) invited me to accompany him to a rather remote (over-grown) area on his property (very near a ‘County Line’ in S.C.) for the expressed purpose to view three [-3-] seldom seen brass/bronze “bench marks” that formed a triad of approx. ninety [-90-] feet. Each bronze marker was mounted atop a rather large (concrete base = the top surface of the base would have probably been less inches (+_), and extended well over 12″ above the ground! I was/am somewhat familiar with some of the local round ‘Bronze Bench Marks’ that in most cases are only a few inches above the ground surface.
QUESTION(s): How rare is such a “triad” as described above? What was
the MAIN reason for such a “triad”? Does an accurate record exist that shows the location(s) of such ‘triads’, and give some general information
concerning the original intended purpose/function of the ‘triad’?
MANY THANKS FOR ANY/ALL TYPE OF RESPONSE!
Regards,
B. LaCoste S. {S.C.}

By: GISGeography

GISGeography — Thu, 11 Feb 2021 12:32:17 +0000

In reply to Pat Barton.

It could definitely be one. It depends where you are from. Have you tried the NGS Data Explorer? It’s worth a shot – https://noaa.maps.arcgis.com/apps/webappviewer/index.html?id=190385f9aadb4cf1b0dd8759893032db

By: Pat Barton

Pat Barton — Tue, 09 Feb 2021 22:30:12 +0000

I think i have a marker in my yard. It’s a round cement but the marker has been removed. Is there a way to know if it is a marker? Is there a web sit that I can put my address in and find out?

By: June travis

June travis — Mon, 17 Aug 2020 04:23:56 +0000

I have a geodetic cement marker in my yard her in Brookhaven Mississippi. Dated 1946 with the name Boone within the circle also what does that mean and is it worth anything

By: Richard B. Davis, PLS

Richard B. Davis, PLS — Sun, 24 Feb 2019 05:29:57 +0000

Many of the early monuments had published data sheets giving horizontal coordinates based on NAD 27. These same monuments now have coordinates based only on NAD 83. I understand that NGS no longer supports or publishes NAD 27 coordinate data, but I need this NAD 27 coordinate data for a research project I am doing in California, Zone 1 . I need access to the original NAD 27 documents that contained published coordinates, and not those converted from NAD 83 that give approximations . Can you please tell me if there is a site where I can still find this NAD 27 coordinate data? Many thanks.

By: Ronald Moe

Ronald Moe — Sat, 05 Jan 2019 05:35:10 +0000

Is there any history noted with named benchmarks?

By: Jean Morin

Jean Morin — Sun, 09 Dec 2018 19:06:33 +0000

How can I log benchmarks that are not listed? I find them all the time, but when I look on the app, Benchmap or on geocaching.com’s website, it doesn’t show up.

By: Julie Prusky

Julie Prusky — Wed, 21 Nov 2018 14:28:29 +0000

Your web site says: “Survey benchmark monuments are brass or metal disks in the ground. They measure exact horizontal positions (latitude and longitude) on the Earth because this gives surveyors a point of reference” Additionally, it says: “A benchmark is a point whose position is known to a high degree of accuracy and is normally marked in some way.”

Benchmarks provide precise orthometric heights. They do NOT necessarily provide precise horizontal positions. Rather, many have scaled positions from maps. Pull any county in the US and you will see both horizontal marks with no orthometric height and BMs with no “adjusted” a.k.a precise positions. It seems the term benchmark is being used interchangeably with geodetic markers or station marker (we even do it at NGS, (sigh)). You may find our FAQs helpful. http://www.ngs.noaa.gov

https://www.ngs.noaa.gov/datasheets/SurveyMarks_FAQ.shtml