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TillaMurphs

Can you help me with topo map symbols?

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I am trying to determine which topo map symbols would represent the location of a disk on topos from 1922 and 1956.

 

 

Here are the topos that I am looking at. I have put yellow highlights near locations in question. Which spots would represent a disk location?

 

igmeFOP.jpg

 

BCVnywl.jpg

 

I have read these 2 documents but I am still a bit confused.

 

- TOPO MAP SYMBOLS - USGS

 

- TOPO MAP SYMBOLS

 

Thanks

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There is an "X" near the BM lettering. The X marks the actual position of the benchmark. But I have found that sometimes that is not completely accurate. Look at the datasheet for the benchmark for the accuracy and the go to description. I have found sometimes the coordinates listed are more accurate than the marks on the map, and sometimes the mark is more accurate.

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As mentioned before, the letters "BM" mean benchmark, which means that a disk was set at the location of the X (vertical benchmark station), or at the location of the triangle (triangulation station). I've also seen instances where a triangle does not have the BM next to it, but there is a triangulation station set there.

 

An X without the "BM" means that the elevation has been determined, but that there is no disk. Often these are at road intersections, for example, or at the top of a hill. In this case, if the X is printed in black, the elevation has been field checked. If the X is in brown, the elevation has not been field checked.

 

My experience has been that topographic maps often do not contain a good number of disks. Some were just never printed on the map. Others are Tidal benchmarks, which seem to be rarely shown on maps. Still others may have been monumented after the last map revisions. Of course, many disks may have been destroyed since the last map revisions, too. And triangulation stations are generally a group of four marks - the station itself, plus two reference marks and one azimuth mark - but the triangle symbol only marks the location of the actual station. You need the NGS datasheet to find the other disks.

 

Hope this helps.

Edited by BenchmarkHunter

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An X without the "BM" means that the elevation has been determined, but that there is no disk.

 

Often these are at road intersections, for example, or at the top of a hill. In this case, if the X is printed in black, the elevation has been field checked. If the X is in brown, the elevation has not been field checked.

 

My experience has been that topographic maps often do not contain a good number of disks. Some were just never printed on the map.

 

Still others may have been monumented after the last map revisions. Of course, many disks may have been destroyed since the last map revisions, too.

 

 

OK - You guys are helping. BenchmarkHunter thank you! And, thank you also Butano.

 

We have hunted for years, but rarely use the USGS topos. So, on these USGS topo maps, if it is an "X" only, with no "BM" or triangle, I should not expect to find any physical object set by a surveyor - is that correct?

This was a general question but currently I am searching for the location of a U.S.G.S. mark set between 1910 and 1919 somewhere in the vicinity of the Yachats River Road on the map. The mark has since been destroyed but may or may not have been recorded as such. I believe the elevation of the mark was 44 feet but I am still trying to confirm that. It looks like the mark was NOT at 64 feet.

 

Thanks

Edited by TillaMurphs

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So, on these USGS topo maps, if it is an "X" only, with no "BM" or triangle, I should not expect to find any physical object set by a surveyor - is that correct?

[/b]

This was a general question but currently I am searching for the location of a U.S.G.S. mark set between 1910 and 1919 somewhere in the vicinity of the Yachats River Road on the map. The mark has since been destroyed but may or may not have been recorded as such. I believe the elevation of the mark was 44 feet but I am still trying to confirm that. It looks like the mark was NOT at 64 feet.

 

Thanks

 

You're welcome for the help. Yes, an X without the BM symbol should not produce a disk. As for the mark you're trying to find... assuming that it's in the NGS database, you can search for it, even without the name of the mark. This should help to narrow the focus of your search, and help you to corroborate the benchmarks shown on the map. Go to http://www.ngs.noaa.gov/cgi-bin/datasheet.prl and click on Datasheets, then enter a search. You might try, for example, entering a "Rectangular Search," which means that you'll search by ranges of longitude and latitude, or a "Radial Search" which means that you'll search for benchmarks that are within a certain distance of a specific longitude and latitude. You do not need to know the designation of the mark for either search, but the mark's designation will be part of the search results. The year that a mark was set is part of the results, so you'd be looking for something set between 1910 and 1919 and, from what you mentioned, marked as destroyed. The second-from-the-right column of the search results is the mark status: S = set and not yet revisited; X = destroyed; N = not found; O = other (bring up the datasheet to see specifics); G = good, P = poor. Unless you know for sure that the mark has been destroyed, don't necessarily rely completely on this status. A mark that's "good" might not have been revisited in decades and has been destroyed. A mark that's "not found" could still exist, and I've seen quite a few datasheets in which the NGS designated the mark as "not found," only to find the mark in a subsequent visit and mark it as "good."

 

As for elevation... older disks were often stamped with their elevation as of when they were set. However, sea level has changed over the past 100 years, so your benchmark's actual elevation today, in the NGS database, is likely a foot or two lower than it was in 1910. Since you seem to know the approximate location of the mark better than you know its elevation, you might narrow your search by location first, and then decide which benchmarks might be yours based on a range of possible elevations, e.g. 40 to 70 feet. With luck, you won't have a very large number of benchmarks to consider.

 

See where this leads you.

 

Hope this helps.

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Hi again BenchmarkHunter,

 

Thanks for the additional information!

 

I should have mentioned that I have already searched the NGS database for this mark - by elevation, station name and location and came up empty - even searching for Destroyed marks. Since this was a USGS disk I did not have a lot of hope that I would find it in the NGS database.

 

That's why I am resorting to historical USGS topo maps as a last resort.

 

Assuming I don't find anything on the topos, and it does not look like I will, I will write to the USGS to have them look through their paper records for the area.

 

Thanks for the help on the topos!

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Tillamurphs,

You can call the USGS and request their benchmark recoveries for that area. I know they have one facility in Rolla, Missouri but think that their west coast facility is elsewhere. I got a few sets of datasheets of my area a number of years ago and used them to search for USGS marks that weren't in the NGS database. You will sometimes find the non-marked ones listed there. As Benchmark Hunter stated they are often the intersections of streets or the center of a railroad crossing, or something like "the top of the rail in front of the Marysville railroad station".

As for the locations of the X's, I have found them to be fairly accurate and a good start for hunting, but not very useful without the description. They will be on the side of the road that they are indicated, for instance, but if they aren't on a bridge or other structure you will have a hard time finding them in the weeds.

I have had some luck finding descriptions by searching for "Spirit leveling" and my state, and found books from the early 1900s that described some of the marks in my area. I did the same for Oregon and got this : http://pubs.usgs.gov/bul/0556/report.pdf, but I don't think it includes the area you want (I searched for Yachats and got nothing). You might also search Google Books for "primary traverse oregon" or "spirit leveling oregon".

 

The USGS accepts recoveries too, although they don't have an online process. I went so far as to write down all the recoveries and never submitted them. Now I feel guilty and will have to dig them out again.

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I believe that the USGS became part of the NGS which is now part of NOAA, so USGS marks from the early 20th Century could/should be in the NGS database. Of course, the operative words are "could" and "should." You can also search in the Archived datasheets, though I doubt that you'd find it there. Remember, of course, that a recovery report that says "not found" is, like our geocaching entries, just a statement that someone couldn't find the mark. The mark could well have existed at the time of the report, but it could have been buried in dirt or sand, or was in a flooded area, or hidden copious amounts of poison ivy. A metal detector may be of use for your recovery efforts, too.

 

One complication that I've found when searching for older marks is that, even with the datasheet, landmark references may have changed. A few examples are that a road was widened, so the mark is closer to the curb than before. A telephone pole was replaced so the distance to that new pole is now slightly different. A bridge was replaced, which could have destroyed the old mark, or part of the old bridge structure was incorporated into the new one and the mark is now at a different distance from other bridge reference points mentioned in the datasheet.

 

As for submitting recoveries, NOAA will take them online: http://geodesy.noaa.gov/cgi-bin/recvy_entry_www.prl . I've heard through the grapevine that NOAA no longer cares much about intersection stations (landmarks) like water tanks, church steeples, radio towers, etc., but does still care very much about benchmark disks. NOAA is still active in this area (NY) and well over 5% of the benchmark disks that I have recovered have been set, or reset with a different PID, within the last 15 years, i.e. not in Groundspeak's database but in the current NGS database, with a trio of Tidal benchmarks set as recently as 2014 and not yet even in the NGS database.

 

Happy benchmark hunting!

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This thread and other recent ones on finding data for NONPID marks kind of ties in with some of my happy thoughts as I've worked on an ongoing project (not sure the winter is going to be long enough) to arrange a sequential, down the river from Three Forks, Montana, slide show of the 1880-90's Missouri River Commission (MORC) permanent bench marks and triangulation stations.

 

Thanks to a copy of a Secretary of War 1891 report provided by square nail, and mentoring from he and CallawayMt (Thanks,guys) I found my first one, NONPID GALLATIN, 10JAN09; and a month later joined them in the recovery of MORC North Base aka CGS G4 - a 1907 PLN. Sadly, after a hundred years (50+ since last recovery) a couple of years of ice jam flooding and high water took the mark. I did touch the stone 6 Oct 2010 and should have removed it!

 

This experience and a friend of my son that wanted to kayak a section of the Wild and Scenic Missouri River in early May 2009 got me looking at all the BM X's on USGS Quad maps, and wondering if they were there. Most are, and very close to the X. Almost all are NONPID's, a few of which I have scabbed onto a nearby MORC Tri and linked to in other threads here. Lots of Google search time (PLN's - Special Publication #18 referred to in above link) prior to the fun field time and now lots of reminiscences.

 

What I'm getting to folks, finally, is that there is a world of bench mark hunting out there that does not require a cell-phone or a log-able find. kayakbird

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>I believe that the USGS became part of the NGS which is now part of NOAA,

 

I don't think so. I've not heard that, and they still have separate web presence.

http://www.usgs.gov/

http://www.ngs.noaa.gov/

 

>so USGS marks from the early 20th Century could/should be in the NGS database

 

Even if the agencies were to be combined, the USGS data is in file cabinets and nobody is going to fund the effort to digitize millions of data sheets on marks that are often not as accurate as the NGS data, especially in these days of precision GPS.

 

>I've heard through the grapevine that NOAA no longer cares much about intersection stations, but does still care very much about benchmark disks.

 

That's official, and will be true at least until the planned new vertical datum is released in about a half-dozen years, based on GPS+gravity at any location instead of the older optically leveled data on the existing marks.

 

>older disks were often stamped with their elevation as of when they were set.

USGS has done a lot of that. CGS/NGS hasn't done that for a long time, if ever.

 

>However, sea level has changed over the past 100 years

 

Actually, irrelevant here. The older National Geodetic Vertical Datum of 1929 (NGVD29) was based on an average of sea level at several locations. Sea level is hard to measure precisely because of tide patterns that take years to repeat, differences in salinity, currents, etc., so locations will not agree with leveling measurements between them.

 

After gathering much more data they released the North American Vertical Datum of 1988, which is still in use. It was based on picking one station and making all others in the US, Canada, and Mexico relative to that one.

 

No adjustment is made in the vertical datum for sea level changes. The difference between datums can be quite significant but varies from region to region. The difference between datums has caused some people to think it is a measure of sea level change, but it is not.

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USGS is part of the US Dept of the Interior (US Geological Survey)

 

NGS/NOAA is part of the US Dept of Commerce (Nat't Geodetic Survery/Nat't Oceanic & Atmospheric Administration)

Edited by Z15

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USGS is part of the US Dept of the Interior (US Geological Survey)

 

NGS/NOAA is part of the US Dept of Commerce (Nat't Geodetic Survery/Nat't Oceanic & Atmospheric Administration)

 

And NGS used to be CGS. From wiki: 'The National Geodetic Survey (NGS), formerly the United States Survey of the Coast (1807–1836), United States Coast Survey (1836–1878), and United States Coast and Geodetic Survey (USC&GS) (1878–1970), is a United States federal agency---' However the Data Sheet will sometimes have NGS as the agency earlier:

 

TM0888 HISTORY - 1923 MONUMENTED NGS

 

I find it easier to just type CGS most of the time. kayakbird

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