Bill93
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Posts posted by Bill93
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The National Geodetic Survey recently published a list of those bench marks they most want professional GPS submissions (OPUS Share) on. That data will be used to help check or fit the 2018 geoid model and 2022 datum.
Many were selected based on their location in areas needing more coverage, and without much emphasis on whether they had been recovered recently. Those marks having no recent recoveries would make excellent targets for everyone to hunt and submit.
Anyone capable of OPUS Share GPS observations may want to use this list to select their targets. I have submitted sessions for 6 of the ones on that list, which I suppose raised their priority for a 2nd checking session. I chose those to be in areas with poor coverage in Geoid12b so they might have made the list anyway.
General info: https://www.ngs.noaa.gov/GPSonBM/ https://www.ngs.noaa.gov/GPSonBM/OnePagerGPSonBenchMarks2018.pdf The latest priority list: https://www.ngs.noaa.gov/GPSonBM/prioritize.shtml Surveyors forum post: https://rplstoday.com/community/gnss-geodesy/surveyors-week-march-18-24-2018-gps-on-bm/#post-463616
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I use BenchMap on an Android, but don't know if it is available on Apple.
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What was the source of the information that a monument exists there? Any clues in that?
Does the USGS topo map show an elevation number there other than just the contour lunes?
Re: buried. An elevation mark may get slightly buried over the years but was visible when set. A triangulation station (for lat lon) was often intentionally buried for protection but would have reference disks set nearby intended to remain visible.
If you do find a disk check what it says.
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In the transfers I've seen, the transfer tax isn't large but is paid on the actual amount regardless of the number in the deed. Likewise the actual is the seller's gross number and buyer's cost basis for capital gains tax.
I don't know about the transfer tac in other jurisdictions.
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NY was not part of the PLSS and as far as I know has only metes and bounds descriptions. People have bought and sold land there in any size and shape they chose, and too often without long-lasting monumentation (trees don't last forever) and imprecise distances. You were lucky if you reached an acceptable and peaceful resolution.
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Okay, he sent me the description. It was a list of 5 pieces each 1/4 of 1/4 section (nominally 40 acres each) and abutting each other. The parsing of such descriptions can be daunting, but he had it figured out to be the same as I did. I'm sure the price included a lot of dollars in addition to the $10 listed.
It works nicely in the earthpoint link above to plot the estimated section lines on Google Earth. This data may or may not show measured positions versus a theoretical calculation from a few reference points. Sometimes the calculations don't match actual, due to the difficulties the original surveyor dealt with, especially in mountainous and thickly forested areas. Also, even if measured, we're not sure to what accuracy. In most cases the monument on the ground rules over math. In one area I'm familiar with the plot shows 40-60 ft mismatches with the roads that are accepted as being on the section lines.
In this case, it shows the sections somewhat distorted from the nominal square shape due to those measurement difficulties. Some of the lines track pretty close to the edge of forested areas, showing that they do reflect recognized boundaries to some level of accuracy.
I should probably clarify that I'm not a surveyor, and haven't yet been asked to play one on TV, but I've been reading the PLSS section descriptions since I was in Jr. High because our local newspaper published the real estate transactions and Dad always wanted to figure out who was selling what farm to who.
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Are you sure it was just $10? It is very common for deeds to avoid stating the actual price. They just list $1 or $10 and "other valuable considerations" (ovc) in order to have something to make it a legal contract.
I'm on my phone so don't want to dig in to the msg stuff here, but if you send me a msg I think I can help with the description.
edit:
For anyone interested, the Wikipedia article is a good start.
https://en.wikipedia.org/wiki/Public_Land_Survey_System
Here's an excellent tutorial on the Public Land Survey System. This example is in Wisconsin, but the ideas apply to most of the states west of the Ohio River and a few in the South, except Texas and certain areas that had private land grants before the US took possession.
https://dnr.wi.gov/topic/forestmanagement/documents/plsstutorial.pdf
This link may be useful for locating a particular description
http://www.earthpoint.us/TownshipsSearchByDescription.aspx
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Benchmark hunting never was or will be as popular (sell as much) as caching. As long as they don't cut back on its support I don't care much.
If caching is declining (I hadn't paid attention), I'd guess
1) most people who might be interested have tried it so entry is now mostly as kids get to an age to do it.
2) it isn't new so it isn't as cool (whatever the fashionable term is now) a thing to do as it was. Pokemon took a lot of people when it was new and hot, for instance.
3) many who tried it for a while have tired of it.
4) there isn't as much challenge and therefore feeling of accomplishment when there is a cache every 0.1 mile in all directions.
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A quick search found some relevant info, although I'm not sure it answers the "when" question.
Old thread:
https://forums.geocaching.com/GC/index.php?/topic/325390-benchmark-in-germany/
These have pictures with German labels.
https://commons.wikimedia.org/wiki/Trig_points_and_benchmarks
https://commons.wikimedia.org/wiki/Category:Wienblickwiese_Grenzstein
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I've seen yards many times in BM descriptions. See QK0329 for instance. It is almost never used for anything that was measured carefully, but not uncommon for "ballpark" distances to get you in the vicinity of a mark.
The other place yards are used almost exclusively is golf.
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17 minutes ago, Z15 said:
Because 120 yds is not precise
That's what I was complaining about. If they had converted to whole meters it would be fine, only a slight change in precision from +/-a couple yards to +/-a meter. But to decimeters??
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I reported a bunch of recoveries in the last couple months, and as I look at the results I see someone is editing them to provide dual units. I submitted one that gave an approximate tie from a field drive crossing the RR tracks. I put it in yards so no one would think I had taped it to the nearest foot. See what I got:
120 YDS (109.7 M) NORTHEAST OF A FIELD DRIVE Aarrgg!
Take heed; do the conversions yourself in your recovery reports so the result doesn't look idiotic.
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Not for the Destroyed report, but I did submit NF saying "probably destroyed" before going back and spending more time with the metal detector to find the actual disks. So it is pretty easy to guess who actually reported it. I "removed the mark from the area to prevent confusion by someone putting it back near where it was."
One of them was discussed and pictured here.
I'm guessing that "Deb Brown" is now a job description and no longer the original person who handled it 15 years ago, and the present person performing that duty just did it differently.
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On 12/3/2017 at 5:08 PM, Bill93 said:
What's missing is action on a couple of destroyed marks
They are now marked destroyed. It's a bit different from ones I submitted years ago in that it says "Reported by Deb Brown" instead of having my name associated with the report.
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The data base has been updated with recovery reports I submitted via web form on Nov 22. That's quite up to date, about 5 working days ago!
What's missing is action on a couple of destroyed marks that I sent in pictures of in July and August and, after seeing no action, duplicated in October. They have my NF reports, but in each case I went back and spent time with the metal detector and found the disk, one in part of the broken post and the other on its pipe laying horizontally under the grass. I'm pretty sure my photos are good enough to be sufficient for a Destroyed.
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That site has changed so the link above no longer works. There are new and informative posts to the thread. See
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You can always go look at the NGS data base for current information. Find the link for Benchmarks, choose your search method, and pick text, not shapefiles.
I quickly tired of finding (or not) green match holders in conifer trees, and decided that while geocaching occasionally took me to interesting places I wouldn't have noticed, it wasn't otherwise a useful activity.
Bench mark hunting (once I got a feel for what the professionals were interested in and how they described positions) lets me make a useful contribution by posting recoveries both here and to NGS, is still treasure hunting outdoors, sometimes involves historical research, and teaches me about geodetic science. I also like playing with some technical toys I acquired for that, including metal detector, magnetic locator, obsolescent theodolite, and now a rather old professional GPS receiver to submit files for GPS on Benchmarks that I've posted about.
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An interesting thread (and links) on the professional forum talks about Michelson's measurement of the speed of light in the 1920's and the assistance the US C&GS gave him. They ran a very long baseline to better accuracy than I can imagine, and triangulated to marks on two mountains. Michelson sent light from one to a mirror on the other and measured the round-trip travel time.
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I agree, but ...
You aren't always concerned with lat-lon. I've been doing OPUS Share submissions that I hope will be accepted for the GPS on Benchmarks program, and wondered if there would be some way to use those vertically mounted disks, for height only and not lat-lon. If you set up the GPS antenna say 50 ft away in the clear, and use an automatic level set at the height of the mark to set the ARP at the height of the mark, anyone who knows how to use the equipment should be able to match within a millimeter or so, well within the expected 2-4 cm accuracy of a 4-hour GPS session. I don't see any way to tie elevation only for the share submission to the PID in the NGS system.
A procedure like this would improve the availability of stable points for GPS vs Leveling comparisons (the point of GPS on Benchmarks), because the other stable old marks are too often not suitable for use. They tend to be on railroad bridges too close to an active track (unless you have the budget for a RR flagman), or on culverts and bridges near a stream with a lot of trees, with more trees when the RR line is abandoned and thus easier to access.
I looked at the data for 25 marks used to create Geoid12B in my area, and was shocked at how many concrete posts they used as opposed to more stable mountings. Only 3 were Stability B. The above paragraph may explain why-posts are more often out in the open.
A side issue is that poured-in-place concrete posts are called C stability, and precast ones are D. I'd have to see evidence before I believed that was warranted. From what I've seen, the precast ones (if they don't get broken) at least guarantee a depth, whereas poured ones that I've seen out of the ground aren't necessarily as long, leaving me wondering about frost heave.
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Anybody can paint a triangle around a point for whatever meaning they want to give it for their own purposes.
I don't see a 2-letter, 4-number PID there, which is the format used by NGS.
I'd suggest that you not pursue the route of finding some mark and then trying to figure out what it is.
Look in the geocaching data base for some marks that have been found by others and locate them yourself to get familiar with what is typically in that data base and the environments where the were typically set.
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It's almost certain these nails do not have high-accuracy geodetic coordinates, and won't be in the NGS data base so you can log them.
They are either cadastral (property corners or reference marks to find those) or for construction (e.g. upcoming road work). A curb is not stable enough over decades, and a nail in a crack less so, but are useful in the shorter term.
The painted numbers you see near those nails are the point identification the surveyor uses on this project, and won't be part of any larger scheme. It is rare to find the NGS PID (like AA1234) marked on an NGS point. Their procedures do not call for marking a PID, just a DESIGNATION. Sometimes a user will paint the PID on the concrete or a stake to help find it during their work in the area.
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Were they measured for inclusion in the data base? That's really what matters for logging here. Generaly, don't bother trying to put them in Waymarking if they weren't in the data base. A nail is usually a temporary mark unless set in a very solid mounting. You won't find many nails in the NGS data base and the geocaching list of benchmarks is an old snapshot of the NGS data.
I HAVE seen a few nails in the data base, but they were part of US Geological Survey work that included disks and got added to NGS, but those nails (usually in wood) weren't really permanent enough and probably shouldn't have been included.
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I found this magnetic station in 2011 and got a short article in the county newspaper. I wanted a commemoration that surveyors might notice also, so I took several hours of GPS data and submitted an OPUS Shared Solution.
These stations were used to measure magnetic declination and to let local surveyors calibrate their compasses by sights to landmarks.
My submission: https://www.ngs.noaa.gov/OPUS/getDatasheet.jsp?PID=BBFS77&style=modern
Find shared solutions: https://www.ngs.noaa.gov/OPUS/view.jsp
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No one can give you permission to keep the disk, so don't ask. Somewhere on the NGS site it says they should be sent back to NGS, but I've never heard of anyone doing that.
There is a procedure for doing a RESET to a nearby position before the old one is destroyed, and reporting the new elevation, but I think it takes a digital level instrument that relatively few surveyors have to get data that NGS will accept.
If this is in a local area with concerns about flooding, you might want to contact a local surveyor who does elevation certificates to alert them about the upcoming destruction. They might want to do their own unofficial reset if that was one they depended on.
It is important to take photos proving the destruction, such as the disk in hand (if you aren't going to be there at the time or get hold of the disk try before and after photos of the site). Send those to deb.brown@noaa.gov so she can mark the data sheet as destroyed.
It IS important to remove a destroyed disk from the area so no one creates confusion by putting it back near "where it used to be," although of course that won't happen to the one you are looking at.
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NGS Priority list for bench mark recoveries and GPS sessions
in Benchmarking
Posted
I probably should have rewritten that to emphasize the need for ordinary recovery reports on many of those marks.
It's a whole lot better if the guy with the gear knows which ones are still out there for him to occupy.