Geodetic Vs Geological Survey's

[+MNSearchers]

I am just trying to get my bearings about this whole benchmark situation and after finding a marker that was presumed destroyed, that really fouled me up. LOL!! Hey this is geomom SoDak Searcher not geodad SoDak Searcher.

So there is a difference between the two? And the geodetic survey markers are the ones that you log on benchmarks at gc.com? And the Geological Survey markers and other misc. ones are logged at Waymarking.com on recovered benchmarks? Plus? Is this benchmarking site on gc.com updated regularly or is it never updated? Because I would think there would be updates to the National Geodetic Surveys database occassionally such as for any new markers they may have found or markers they thought were destroyed and such. Thanks in advance for any answers.

[Bill93]

The list that Groundspeak uses on their Benchmark site is a snapshot taken in about 2001 from the National Geodetic Survey, formerly called the Coast and Geodetic Survey. NGS maintains an on-line data base that can be searched and is constantly being updated with recovery reports, corrections, and new marks, but Groundspeak does not have a way to capture those updates.

 

The NGS list includes markers set by themselves and others, that were very accurately measured (horizontal, vertical, or both) and their data processed in a prescribed manner. Many markers in this list were set by the US Geological Survey, state agencies such as Dept of Natural Resources or Dept of Transportation, cities, and others. See the forum thread "Disk Logo List" for an extensive listing.

 

However, the number thus included in the NGS list is a very small fraction of the markers set by those other entities. Generally those other agencies do not have on-line data bases. Zhanna's site has links to a few that are known.

 

Because there are so many disks that can't be logged on the Benchmark site, they created the Waymarking category. The criterion for where to log is not who set the disk, but whether or not it is in the 2001 snapshot of the NGS data base.

[Z15]

Also NGS will not publish any mark for which they do not have the field notes to verify the intergrity of the marks data. And by field notes I mean all the measurements, climatelogical data, instruments used and descriptive data. USGS was doing work to different standards for map making than CGS/NGS was doing for geodetic control.

 

The USGS has never provided that info to NGS and likely never will due to the massive amount of paper it entails, it would be cost prohibitive.

 

The USGS marks in the NGS DB positions were derived from work done by the NGS or other angencies and that info is in the records of the NGS.

 

Due to the methods employed and the inprobabilty of recovery, USGS deems many of them obsolete and do not warrant any futher work to preserve them. In other words, expendable.

Edited August 8, 2006 by Z15

[StripeMark]

Due to the methods employed and the inprobabilty of recovery, USGS deems many of them obsolete and do not warrant any futher work to preserve them. In other words, expendable.

 

So in other words, if a USGS marker, which is also being used by the NGS and on the NGS database, is marked DESTROYED by the NGS, USGS won't care about it?

 

I found a USGS marker a while back that got labeled DESTROYED on the NGS database and was wondering if I should e-mail Rolla, MO, (for the eastern US) about it.

 

I knew all their datasheets are on paper and sitting in a dark room in a file cabinet. And yes, it would take way to long, and cost too much money, to try and get all the USGS datasheets on-line.

 

When I visited the USGS at Rolla last summer, they had the datasheets for local marks in a PDF file that they would just print off to use.

[+Ernmark]

So in other words, if a USGS marker, which is also being used by the NGS and on the NGS database, is marked DESTROYED by the NGS, USGS won't care about it?

 

...this is the same situation I've encountered as I mentioned in an earlier thread (although I haven't submitted destruction info to the NGS yet). During a recent visit to a local USGS office, the person there said they still must have the disk ...although I know others here have been told differently (I think my area office wants to beef up their lobby display)..

[Z15]

When dealing with gov't agencies you are likely to get a different answer from everyone you talk to. In my 30 yrs of finding destroyed marks, they never asked us for them back. We even had new USGS disks to use for resetting bench marks.

 

I am not saying all of the marks are obsolete, just there are many that are. Also, in many areas 95% of them do not exist anymore due to changes in the landscapes. More than 95% of them in my area are long gone because the roads have changed from 1 lane gravel to 2 land blacktop.

Edited August 9, 2006 by Z15