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trailwalker

Learn about a USGS benchmark I found

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I've been geocaching off and on since 2002. On a recent hike, I found a benchmark (image inserted below). I was trying to figure out how to get information about this benchmark and others. This one is listed on my topo maps (I use EasyGPS). There is a "BM" and "X" at the spot. But I can't find it in a database. Do some of these benchmarks become abandoned after a time? This one is literally right on the Appalachian Trail and has been substantially defaced, so a lot of people have seen it. I can't see that it has been logged on this Geocaching site. Why can't I find it listed in any databases? When I list the coordinates, I can find benchmarks in the area, but this location isn't among them. From what I can tell, most people who do benchmarking are finding a benchmark listed in the database first and then going out to find and log it. I guess I'm trying to do the opposite. Sorry for the long post, but I'd like to get started in benchmarking and am not quite sure how to do that.

IMG_1171v2.jpg

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I'm not a benchmark expert, but it looks like most benchmarks were placed by the US Coast & Geodetic Survey (now called National Geodetic Survey or NGS). Your benchmark looks like it was placed by the US Geological Survey, which doesn't appear to have an online database. The USGS website has some phone numbers and email addresses if you want more information on your benchmark. http://www.usgs.gov/faq/node/2619

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Can you post the coordinates, nearby Geocache or other info of something nearby of where you found the USGS BM. Some BM's don't ever make it into the NGS database because they have no, 'descriptive or observational data' so they're not publishable. I'm sure someone else could cite additional reasons.

 

There are a lot of knowledgeable BM'ers on this forum and I'm sure everyone has their own technique for BM'ing.

 

Most often I use my Iphone with the Hunt Markers app. It's similar to the Groundspeak Geocaching app. It'll display BM's and their PID numbers for BM's near your present location or by using a couple of other adjustable parameters. For some reason you have to search for it as, 'FindMarkers' in the app store. I believe it also works with the Samsung's.

 

If I want to research & target specific BM's, whether it be by agency, location, state, county, type, route, etc.; I have all my Florida BM's from the NGS database loaded into GSAK. I keep the 3 surrounding counties loaded into my GPS and I'll turn it on occasionally when I'm on the road to see what's in the area. When I travel, I'll load all the destination BM's into the GSAK and my GPS. I've taken an interest in the U.S. Coast & Geodetic Survey disks so I most often search them out.

 

This is a very good paper on BM's. http://www.ngs.noaa.gov/web/about_ngs/history/Survey_Mark_Art.pdf

 

Tools: I carry gloves, two small garden shovels, a probing tool (Craftsman Rolling Wedge Bar), measuring tapes 100' & 300', small wisk broom, rags and water to wipe off disks, and now an inexpensive metal detector from Harbor Freight. The metal detector definitely allowed me to locate BM's I would never have found without it. Case in point, PID AC4642 & AR1564.

Don't forget the camera! I try to take at least 3 pics; 1 closeup, 1 from above 3-4' and 1 from a distance to show some nearby references and bearing.

 

I hope this helps a bit.

139bfbe6-dbb5-4bf6-94d7-44413d9d2228.jpg

Edited by Gungadoy

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I'm not a benchmark expert, but it looks like most benchmarks were placed by the US Coast & Geodetic Survey (now called National Geodetic Survey or NGS). Your benchmark looks like it was placed by the US Geological Survey, which doesn't appear to have an online database. The USGS website has some phone numbers and email addresses if you want more information on your benchmark. http://www.usgs.gov/faq/node/2619

 

Ahh ... that would certainly explain it. I'll poke around a bit and see if I can find anything out about USGS benchmarks. Appreciate your help!

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Can you post the coordinates, nearby Geocache or other info of something nearby of where you found the USGS BM. Some BM's don't ever make it into the NGS database because they have no, 'descriptive or observational data' so they're not publishable. I'm sure someone else could cite additional reasons.

 

There are a lot of knowledgeable BM'ers on this forum and I'm sure everyone has their own technique for BM'ing.

 

Most often I use my Iphone with the Hunt Markers app. It's similar to the Groundspeak Geocaching app. It'll display BM's and their PID numbers for BM's near your present location or by using a couple of other adjustable parameters. For some reason you have to search for it as, 'FindMarkers' in the app store. I believe it also works with the Samsung's.

 

If I want to research & target specific BM's, whether it be by agency, location, state, county, type, route, etc.; I have all my Florida BM's from the NGS database loaded into GSAK. I keep the 3 surrounding counties loaded into my GPS and I'll turn it on occasionally when I'm on the road to see what's in the area. When I travel, I'll load all the destination BM's into the GSAK and my GPS. I've taken an interest in the U.S. Coast & Geodetic Survey disks so I most often search them out.

 

This is a very good paper on BM's. http://www.ngs.noaa.gov/web/about_ngs/history/Survey_Mark_Art.pdf

 

Tools: I carry gloves, two small garden shovels, a probing tool (Craftsman Rolling Wedge Bar), measuring tapes 100' & 300', small wisk broom, rags and water to wipe off disks, and now an inexpensive metal detector from Harbor Freight. The metal detector definitely allowed me to locate BM's I would never have found without it. Case in point, PID AC4642 & AR1564.

Don't forget the camera! I try to take at least 3 pics; 1 closeup, 1 from above 3-4' and 1 from a distance to show some nearby references and bearing.

 

I hope this helps a bit.

139bfbe6-dbb5-4bf6-94d7-44413d9d2228.jpg

 

Thanks for these tips, Gungadoy. I use an iPhone sometimes, too, but usually I use my Garmin. I didn't take these coordinates while I was at the site of this benchmark, but on the map they are 40.61146 North and 75.96521 West. This is right along the Appalachian Trail below the Port Clinton fire tower in Berks County, PA. As the previous commenter pointed out, this is a USGS survey marker and I was attempting to look it up in NGS databases, which would explain why I couldn't find it. Again, I appreciate your tips on getting started with benchmarking.

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Basically it boils down to that when NGS was compiling data for inclusion into the national database circa 1980, USGS did not provide any information, likely due to budget constraints. USGS over the years had very copious notes and scatted in various locations. I suppose the cost to compile all this information was time consuming and costly so a decision was made that is was not in USGS interests to do that. Today many of the USGS marks are of sub-standard accuracy so they have no need to ever use them again. Due to the methods employed and the improbability of recovering them, USGS does not deem them important. Its cheaper to go out and set new mark with GPS than to spend 5x as much time looking for old one. Many are just merely historical in nature today due to advancements in survey technology (GPS).

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Basically it boils down to that when NGS was compiling data for inclusion into the national database circa 1980, USGS did not provide any information, likely due to budget constraints. USGS over the years had very copious notes and scatted in various locations. I suppose the cost to compile all this information was time consuming and costly so a decision was made that is was not in USGS interests to do that. Today many of the USGS marks are of sub-standard accuracy so they have no need to ever use them again. Due to the methods employed and the improbability of recovering them, USGS does not deem them important. Its cheaper to go out and set new mark with GPS than to spend 5x as much time looking for old one. Many are just merely historical in nature today due to advancements in survey technology (GPS).

 

Thanks for this clarification, Z15. I was just curious about this benchmark that I found and trying to learn what I could about it. Your info is helpful.

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How can I find survey benchmark and triangulation station information?

 

Most survey marks were set by the US Coast & Geodetic Survey (now called the National Geodetic Survey) and information for those marks is available on the web. For further assistance call 301-713-3242 or e-mail infocenter@ngs.noaa.gov. If the National Geodetic Survey doesn’t have the information you seek, contact one of these two offices:

 

For information about marks set by the USGS in ND-SD-NE-KS-OK and all points east, contact USGS in Rolla, Missouri, by telephone at 573-308-3500 or by e-mail at mcmcesic@usgs.gov.

 

For information about marks set by the USGS in MT-WY-CO-NM-TX and all points west, contact USGS in Denver, Colorado by telephone at 303-202-4200 or by email at answerspgm@usgs.gov.

 

They will need to know the state and other info such latitude, longitude, location, name of the USGS map its shown on and everything stamped on the disk, not whats cast into it. Keep in mind it all paper so it requires some work to look for so more information speeds the process.

 

Here is a link that shows a typical USGS data sheet

Bench marks----> http://surveymarks.planetzhanna.com/USGS/MI/Houghton_356.pdf

Traverse marks-----> http://surveymarks.planetzhanna.com/USGS/MI/H_Houghton_356.pdf

Edited by Z15

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One tiny additional clarification note: Out west many, many USGS marks are included in the NGS data Base - also quite a few early 1900's GLO's. (Hint: search PLSS). kayakbird

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ECKVILLE, 1.7 MILE SOUTH OF ON APPALACHIAN TRAIL; 50 FEET SOUTH OF STREAM CROSSING; 6 FEET WEST OF CENTER OF ROAD; IN TOP OF 3- BY 4- BY BOULDER; STANDARD TABLET STAMPED

" 6 EOM 1946 1075 "

 

1074.539 FEET ( DATUM OF 1929 )

FROM:

USGS-Rolla, MO

Office of Communications and Publishing

Science Information Services

888-ASK-USGS (275-8747)

Edited by Gungadoy

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As the previous commenter pointed out, this is a USGS survey marker and I was attempting to look it up in NGS databases, which would explain why I couldn't find it.

As Kayakbird noted, there are lots of USGS marks in the NGS database, along with marks from hundreds (thousands?) of other agencies. Most of the several dozen survey marks I've found in Yosemite were installed by the USGS. I never realized, though, that this might be more common in the Western U.S.

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Keep in mind NGS uses North American Datum 1983(NAD83) Geocachers use World Geodetic System 1984 (WGS84) These are two totally unrelated datums and there is not a reliable conversion. If you are going to look for a benchmark or map a benchmark you need to change the datum in your GPS to NAD83.

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The difference between NAD83 and WGS84 is on the order of one meter (3 feet) in most of the US and therefore not important at recreational GPS accuracy. See a fuller response in another thread.

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