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traildad

What is this-Elevation Marker?

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Hello. I found this marker next to a micro cache I found. I tried to look it up online and I could not find any info. I was wondering if it is of any significance. It says;

U.S. Geological Survey Benchmark

10

TKM

Elevation

Above Sea

227 feet

1941

 

It is in the town of St. Helena in Napa County California at Silverado Trail and Fawn Park Rd.

Thanks Ken

 

2ff44e32-97ac-4555-9b5d-3139d1f09e19.jpg

Edited by traildad

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Hi, traildad,

 

Welcome to benchmarking.

 

Most survey and control markers that have been placed by various government and private entities are not in the National Geodetic Survey database used here on Geocaching.com. (The Geocaching database hasn't been updated since it was originally captured around 2001, so newer marks that are in the NGS database won't appear here either.)

 

Your best bet is to do a lat/long search for your mark on the advanced search page, but first I recommend you read the FAQ, especially the section near the bottom, "I found a benchmark, but it isn't in your database. Why?"

 

-ArtMan-

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This is one of the many thousands of survey control points established by the U.S. Geological Survey (USGS) and never submitted to NGS for inclusion in the National Spatial Reference System. The USGS control data sheet for this station indicates that it was set under the direction of Chief-of-Party T.K. Moe and was established as vertical control only with an NGVD 29 height of 227.229 ft.

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Even though it's not in the NGS database, this marker (at 38 31.4 N, 122 28.6 W) is shown on the USGS topographic map for that area:

 

sthelenabh6.jpg

 

Ken

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Aren't the BMs indicated on Topo maps set almost exclusively for topographic purposes?

Somewhat similarly to the case for cadastral marks, very few seem to be included in the set of marks we are working with. I did find a crossover last week, though. TTP 22

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Aren't the BMs indicated on Topo maps set almost exclusively for topographic purposes?

Somewhat similarly to the case for cadastral marks, very few seem to be included in the set of marks we are working with.

I'm a relative newbie to benchmarking, but based on what I've seen in the Maptech TNPro program, I think the majority of USGS benchmarks are included. It may vary depending on geographic region, but below is a screenshot from a map in south Texas where all BM symbols correspond to NGS entries, which are shown by the red triangles. You can click each red triangle in the software to see the datasheet entry in the NGS database.

 

lissiema0.jpg

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I'm a relative newbie to benchmarking, but based on what I've seen in the Maptech TNPro program, I think the majority of USGS benchmarks are included. It may vary depending on geographic region, but below is a screenshot from a map in south Texas where all BM symbols correspond to NGS entries, which are shown by the red triangles. You can click each red triangle in the software to see the datasheet entry in the NGS database.

 

You're fortunate. Hawaii is littered with little Xes and dotted triangles and squares, but I've found very few in the databases. :/ I'm finding plenty of other anonymous bolts, pins, pipes and stakes stuck all over the place in the lava, as well. I'm always trying to dig up the history of these things.

Edited by bkrownd

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I'm a relative newbie to benchmarking, but based on what I've seen in the Maptech TNPro program, I think the majority of USGS benchmarks are included. It may vary depending on geographic region, but below is a screenshot from a map in south Texas where all BM symbols correspond to NGS entries, which are shown by the red triangles. You can click each red triangle in the software to see the datasheet entry in the NGS database.

 

You're fortunate. Hawaii is littered with little Xes and dotted triangles and squares, but I've found very few in the databases. :/ I'm finding plenty of other anonymous bolts, pins, pipes and stakes stuck all over the place in the lava, as well. I'm always trying to dig up the history of these things.

 

Are you talking about Xs on the Topo maps or on the ground?

 

Survey crews on Oahu seem to make a lot of chiseled crosses on sidewalks or in the road for their construction project. I doubt you would find any information on these except in the plans of that project.

 

I find most of the Xs on the topo maps correspond with an NGS benchmark and the triangles with triangulation stations. Which is what I would expect.

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A lot of the unknown disks that people post here in the forums are USGS disks. There are chains of them in New Mexico that aren't in the NGS database; I've copies of a few quads around Albuquerque. Most of the disks do not have associated Xs. I would echo DaveDs comments.

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