Summit Benchmarks

[4000'er]

4000'er, any chance you could make the whole set available when you're done?

Sure, No problem

 

[elhefe007a]

Here are a couple off hand -



The old "Potato Hill" marker on Mount Abraham (VT).
http://www.forthoseabouttorock.net/climb/NE/abrahamvt/SummitMarker2.jpg


The only Old Speck (ME) benchmark we could find. (Apparently there were 3...)
http://www.forthoseabouttorock.net/climb/NE/oldspeck/summitmark1.jpg

 

[RoySwkr]

To get survey marker descriptions from NGS:
http://www.ngs.noaa.gov/cgi-bin/datasheet.prl

The Coast & Geodetic Survey typically set marks for commerce whereas the USGS set theirs to make maps. Different government agencies.

Actually the Coast & Geodetic Survey (now renamed & part of NOAA) is responsible for the most precise surveys of the national grid, with very little relation to commerce.

Many other agencies set survey marks, including Corps of Engineers, Army, TVA, state highway departments, just read the marker.

Many triangulation stations have one or more reference marks. Trus bench marks never have any.

Can you provide a reference for this statement?

Question of the day: older USGS markers say something like "fine of $250 for disturbing" while newer ones say $500. What will it cost you to remove an old one

 

[askus3]

Here is my contribution: a blurred photo of the benchmark under the summit observation tower on Carrigain. At least I came out clear.

 

[Nate]

Shrinking Mountains

I wonder, how often are the elevations of mountains re-measured? I ask because since it's a measurement based on height relative to sea level, if global warming isn't reversed in time and the polar ice caps continue to melt, the increased sea level will mean the mountains will increasingly lose elevation. Hence, yet another downside to the global warming scenario: the northeast won't have as many 4k's. And yet we object to windfarms because they're not pretty.



("Hey, why's there a canister on this mountain? It's only about 1200' high!")

 

[Papa Bear]

I wonder, how often are the elevations of mountains re-measured? I ask because since it's a measurement based on height relative to sea level, if global warming isn't reversed in time and the polar ice caps continue to melt, the increased sea level will mean the mountains will increasingly lose elevation. Hence, another downside to the global warming scenario: the northeast won't have as many 4k's. And yet we object to windfarms because they're not pretty.
("Hey, why's there a canister on this mountain? It's only about 1200' high!")

Actually,they no longer measure elevations from sea level. Most older maps were based on what is called the "1929 datum" or zero point for elevation (and another one for locations). This was called the NGVD 29 (National Geodetic Vertical Datum of 1929). The problem was this was constrained to be zero for all the tidal measurement stations on the east and west coast, and it resulted in a warped surface. The sea was basically not level.

So in 1988 they went to NAVD 88 (North American Vertical Datum of 1988) which was constrained at just one point (a tidal station on the St Lawrence River in canada) and the surface was rationalized as a very good matematical model of the earth's shape. (see NGS FAQ on Datums)

As a result, zero on the east coast is under water and zero on the west coast is above the water (basically because the water sloshes against the east and away from the west coast, because of the rotation ofd the earth). This datum also makes it possible to use a consistant model for GPS usage.

NOS has tidal stations all over the place that meeasure mean sea level and they see long and short term variations.

Check this site: NOS site. They actually show real time tide data if you can navigate down (can't remember at this moment).

 

[Papa Bear]

The Coast & Geodetic Survey typically set marks for commerce whereas the USGS set theirs to make maps. Different government agencies.

Actually the Coast & Geodetic Survey (now renamed & part of NOAA) is responsible for the most precise surveys of the national grid, with very little relation to commerce.

Department of Commerce -> NOAA -> NGS (formerly C&GS)

Department of the Interior -> USGS

 

[DougPaul]

Actually,they no longer measure elevations from sea level.

The vertical reference is a geoid--a gravitational equipotential surface (ie a surface where the force of gravity is the same everywhere). The chosen equipotential surface has an average height equal to that of mean sea level. http://en.wikipedia.org/wiki/Geoid.

The shape of the geoid can be inferred from satellite orbits as well as from ground measurements.

The estimate of the geoid is updatded periodically. http://www.ngs.noaa.gov/GEOID/GEOID99/

There are several comments about the vertical datum in the faq:
http://www.ngs.noaa.gov/faq.shtml#WhatNAD
http://www.ngs.noaa.gov/faq.shtml#WhatVD29VD88

Doug

 

[lumberzac]

Here's the one on Gothics
http://community.webshots.com/photo/128559385/1128561056048978467kiTQvE

I wish I took a picture of the one on Dix (or maybe it was on Noonmark) the other weekend. I believe it was one that was placed there during the Colvin survey (it had an 1890's date on it).

 

[Tom Rankin]

Here's the one on Gothics
http://community.webshots.com/photo/128559385/1128561056048978467kiTQvE

I wish I took a picture of the one on Dix (or maybe it was on Noonmark) the other weekend. I believe it was one that was placed there during the Colvin survey (it had an 1890's date on it).

Nice!

I'll post Noonmark in a few hours. Forgot about that one, and yes, it is an old Colvin bolt!

 

[Papa Bear]

Here are some entries for peaks I have climbed. I have also recorded hundreds of benchmarks which are not on summits (many of these are in NY City) but that's another story.

Besides the NGS retrieval page given above, those interested should be aware that Geocaching.com, normally concerned with that hobby, has a vast colection of benchmark records. The link is here: Geocaching Benchmark page. Besides searching by PID or Zip code, you can see the gallery which has many thousands of pictures.

I'll give links to my entries on that site, of which I am a member, since each entry often has multiple pictures and a bit of a log. There is also a clickable map with each entry. You are welcome to use any of my photos from the site, but be aware there are also entries from numerous others.

The last group, from last week were all IBC markers, a category set by the US-Canadian group that takes care of the border. Unfortunately these look all alike (up close) since there is no stamping.

Enjoy.

Chain of Ponds Snow
Mt Moxie
Mt. Mansfield
Note there is another benchmark nearby which is a hole in the rock inside a triangle. The one pictured is USGS, the hole is C&GS
The Traveler
Carrigain

IBC stations from last week:

E. Saddle Hill
W. Monument 443 peak
Boundary Peak (HH)
Monument 447 Peak
W. Smart (Layton)
Bump

Regards

 

[Tom Rankin]

Noonmark

http://viewsandbrews.com/temp/Noonmark.jpg

Hard to read the date...

 

[Pete_Hickey]

I've got a meta-benchmark picture here.

http://newmud.comm.uottawa.ca/~pete/julie46/julie46F.jpg

It's a picture of someone taking a close look at Colvin's marker on teh summit of Dix.

As an aside... What kind of mother would name her baby "Verplank? What did the kids at school call him?

EDIT: Link fixed.

 

[Tom Rankin]

http://newmud.comm.uottawa.ca/~pete/julie46F.jpg

Bzzt! 404

 

[Pete_Hickey]

I wish I took a picture of the one on Dix ....

Which one? There are at least 4 on Dix. At least 3 USGS markers, as well as Colvin's. Next time I'm up there, I'll try to remember to photograph them.

 

[lumberzac]

Which one? There are at least 4 on Dix. At least 3 USGS markers, as well as Colvin's. Next time I'm up there, I'll try to remember to photograph them.

The Colvin bolt. No need to take a picture for me. It just gives me an excuse to climb it again and get the picture myself.

Hmmm, I think I need to return trip to Dial for the same reason.

 

[4000'er]

This thread had been very helpful. Thank you to all who have contributed. I could use some more NH bench mark disk photos...

Thanks again everyone.

 

[RoySwkr]

Note that the meta-photo shows the Colvin bolt on Dix

Hey PH, do you have a photo of the Santanoni disk before somebody stole it?

 

[lumberzac]

Note that the meta-photo shows the Colvin bolt on Dix, along with some nut

Hey PH, do you have a photo of the Santanoni disk before somebody stole it?

Is that the one that said "Panther" on it?

 

[Tom Rankin]

If you want a bigger version of my current avatar, PM me...

BTW: Is the complete collection available anywhere?