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Survey Accuracy

2009-05-20 00:06:56.317271+00 by ebradway 12 comments

There have been some recent reports about the Four Corners monument being in the wrong place. The National Geodetic Survey recently issued an official statement clarifying the issue. It's interesting to note how legal descriptions interact with technical accuracy:

Indeed, the monument marks the exact spot where the four states meet. A basic tenet of boundary surveying is that once a monument has been established and accepted by the parties involved (in the case of the Four Corners monument, the parties were the four territories and the U.S. Congress), the location of the physical monument is the ultimate authority in delineating a boundary. Issues of legality trump scientific details, and the intended location of the point becomes secondary information. In surveying, monuments rule!

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comments in ascending chronological order (reverse):

#Comment Re: made: 2009-05-20 13:36:34.433377+00 by: Dan Lyke

I love the phrase "Issues of legality trump scientific details".

#Comment Re: made: 2009-05-20 14:32:14.202719+00 by: jeff

I had to laugh out loud about that one too!

#Comment Re: made: 2009-05-21 02:22:55.343686+00 by: Mark A. Hershberger

http://bit.ly/lmAZL # Link to Google Maps satellite view

Looks like its at the corners to me! Of course, I wasn't aware of that tiny wedge in the corner of the Colorado/Utah border.

#Comment Re: made: 2009-05-21 12:06:19.15356+00 by: Larry Burton

It looks like it is totally in New Mexico to me.

#Comment Re: made: 2009-05-21 13:39:06.647083+00 by: Dan Lyke

Also looks like it's not at exactly 39° -109°.

#Comment Re: made: 2009-05-21 14:29:32.962026+00 by: ebradway

Beware, Google manipulates their vector data to get it to line up with raster. That is, the lines drawn on top of the "satellite" photos are moved to match the photos. This is exactly opposite of how it "should be done".

And the point of the article is that it's not supposed to be at 39N, 109W. The original legal description of the border between New Mexico and Arizona was based off the old Washington Meridian, which wasn't at an whole longitude degree.

#Comment Re: made: 2009-05-21 15:28:34.196646+00 by: petronius

"When the legend becomes history, print the legend"

#Comment Re: made: 2009-05-21 21:21:19.257927+00 by: TheSHAD0W

The real problems occur when you have two "official" monuments that contradict each other; that has created some horrible legal battles.

#Comment Re: made: 2009-05-21 21:21:50.908713+00 by: TheSHAD0W

Oh yeah, and pi = 22/7. It's the law!

#Comment Re: made: 2009-05-21 21:45:57.74701+00 by: Dan Lyke [edit history]

Eric, yeah, the Google Maps/Earth alignment is making me wonder some things about iPhone GPS accuracy...

I thought the article said was that it was supposed to be there (fixing my typo of 39 to 37), specifically the paragraph which starts:

The National Geodetic Survey said the location of the Four Corners was determined to be at 109 degrees west longitude and 37 degrees north latitude during the 1868 survey of Colorado's southern boundary line...

That is that the surveyors were supposed to find 109°W 37°N, said they did, put the monument there, and that's not where they actually were. At least most of the error was in longitude, that's a more understandable goof than latitude.

And one of the non-goofs that I've heard attributed to goofs is in areas like the midwest where you have roads laid out on mile grids, every few miles when driving north to south the road will jog. People are likely to attribute this to surveying error, but it's just the problem of laying a square grid on a spherical surface.

#Comment Re: made: 2009-05-21 22:01:30.598468+00 by: jeff


Are you guys telling me that, when I put one foot in one state, another foot in a different state, and both hands in different state that I'm now going to have to go back and do it all over again? Don't ask me which foot or hand went where!

#Comment Re: made: 2009-05-23 06:00:26.318441+00 by: ebradway

Jeff: It's one foot in one state, another foot in a second stand, both hands in two other states with another appendage in a fifth state.