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Old 04-22-2009, 11:06 AM
 
Location: Albuquerque
5,553 posts, read 9,425,776 times
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Readings Show Four Corners Marker Off By 2.5 Miles - Seattle News Story - KIRO Seattle (http://www.kirotv.com/news/19240434/detail.html - broken link)

USA Today - Four Corners misses mark by 2.5 miles

I say move the borders to reflect the actual location of the monument.

KOAT Albuquerque - Readings Show Four Corners Marker Off By 2.5 Miles
(http://www.koat.com/news/19232758/detail.html - broken link)
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Old 04-22-2009, 11:06 AM
 
Location: New Mexico USA
17,453 posts, read 18,525,729 times
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Quote:
Originally Posted by AlisonL View Post
I would not rely on our GPS to find anything. Half the streets in NM don't even show up on it,
That is because your software does not have the street map.

GPS can find a point on the earth the size of a nail head. But the GPS does not know what is there. It can take you back to that point or determine your coordinates.

It is actually pretty amazing.


Rich
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Old 04-22-2009, 11:15 AM
 
Location: United Kingdom
339 posts, read 839,247 times
Reputation: 173
Quote:
Originally Posted by Poncho_NM View Post
That is because your software does not have the street map.

GPS can find a point on the earth the size of a nail head. But the GPS does not know what is there. It can take you back to that point or determine your coordinates.

It is actually pretty amazing.


Rich
I was under the impression that GPS resolution was limited to about 5M for the general public to save on satellite processing time etc, but the military could get accuracy to within 5CM
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Old 04-22-2009, 12:30 PM
 
Location: 38 38' 45" N, -90 20' 08" W
7,646 posts, read 11,368,171 times
Reputation: 6179
Quote:
Originally Posted by mortimer View Post
Readings Show Four Corners Marker Off By 2.5 Miles - Seattle News Story - KIRO Seattle (http://www.kirotv.com/news/19240434/detail.html - broken link)

USA Today - Four Corners misses mark by 2.5 miles

I say move the borders to reflect the actual location of the monument.

KOAT Albuquerque - Readings Show Four Corners Marker Off By 2.5 Miles
(http://www.koat.com/news/19232758/detail.html - broken link)
There are a bunch of points I have to make regarding this thread. I'll start with Mortimer's assertion of moving the borders to reflect the actual location of the monument. This would seem rational and logical, however, many more borders also have to be moved. The four corners survey actually post-dates many others that were made in this country that define modern day boundaries, including the most high profile survey, the Mason-Dixon survey. If all surveys today were re-done based on ancient title deeds, there would be much litigation in the federal courts.

I will try not to bog this part of my post down into highly technical jargon, so here it goes: the four corners survey was conducted using a completely different datum than the one that exists in the present day. A datum is essentially the reference specifications of a measurement system, in coordinate positions, either horizontally or vertically. The datums that have been used over history have varied, being superseded by superior measuring techniques. These techniques evolved over time as geodetic scientists were able to garner an appreciation for the shape of the earth. In the beginning, the earth was thought to be a perfect sperhoird, but over time, the x and y flattening and orientation was taken into account: the earth bulges out more at the equator than at the poles. Therefore, the distance from the north pole to the south pole is shorter than is the distance from Greenwich meridian to the International Date Line is, at the equator. This was not acknowledged in the 1800s.

The state of New Mexico conducted its own survey in the 1920s, to divide the state into logical land parcels for undeveloped land. (There are outliers in this survey, such as metes and bounds for Spanish and Mexican land grants that shatter the gridiron pattern) This survey was conducted using another geodetic datum, in this case the North American Datum of 1927. This datum is applied for the lower 48 states, and assumes a known point in Meades Ranch Kansas, the geographic center of the lower 48 states. Herein lies the initial likelihood for discrepancy.

Now consider, in chronological terms, all the land boundary surveys that have been conducted since colonial times, and how they vary, as time goes on. The Clark survey conducted that measured the New Mexico-Texas boundary was more than 2 miles inaccurate, as later proved. This survey occurred in 1859. Subsequent to that survey, the proper 103rd meridian was uncovered to survey the Oklahoma-New Mexico boundary. If you zoom into the point where the three state boundaries converge, you'll observe a 2 mile offset between these boundaries. Yet, it is rarely remarked upon or even observed.

As a final observation, going back to the PLSS survey, I possess data where survey monuments are SUPPOSED to reside, using the 1927 NAD survey markers. However, in 1980 the International Union of Geodesy and Geophysics refined (once again) the criteria in which datums are callibrated. Previously, these datums were callibrated from a known point on the earth's surface. The geodetic reference system of 1980 redefines this criteria. The datums now commonly used are now geocentric, which means that now, rather than the point being derived from a known point on the earth's surface, now, the horizontal geodetic datum based on an ellipsoid that has its origin at the earth's center of mass. The reason for doing this was to accommodate at that point the emerging technology of satellite positioning systems. Why do I mention this? Because I have had the pleasure of converting the NM survey monuments, conducted in the 1920s and 30s, derived from the NAD 1927 datum, into the NAD 1983 datum, which is formulated from the GRS 1980. If I convert these monuments into waypoints and navigate to them, they are RARELY where they should be. The tolerance threshold is typically anywhere between 3 and 50 + feet.

I only offer up this post to illustrate how inexact our entire U.S. land boundaries are. This article is not surprising, in fact, given the history and evolution of survey techniques, it should be very understandable.
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Old 04-22-2009, 12:31 PM
 
Location: 38 38' 45" N, -90 20' 08" W
7,646 posts, read 11,368,171 times
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Quote:
Originally Posted by collinsl View Post
I was under the impression that GPS resolution was limited to about 5M for the general public to save on satellite processing time etc, but the military could get accuracy to within 5CM
This was true prior to 2000:
President Turns Off GPS Selective Availability
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Old 04-22-2009, 12:53 PM
 
3,068 posts, read 5,299,867 times
Reputation: 1777
Quote:
Originally Posted by Poncho_NM View Post
That is because your software does not have the street map.

GPS can find a point on the earth the size of a nail head. But the GPS does not know what is there. It can take you back to that point or determine your coordinates.

It is actually pretty amazing.


Rich
So this means we would have to update it with a new one? No way. Not into gadgets and its not something we have to have. I got sick of it constantly "talking". I find it as annoying as a cellphone.
I am technology challenged and intend to stay that way. LOL
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Old 04-22-2009, 01:07 PM
 
Location: New Mexico USA
17,453 posts, read 18,525,729 times
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Quote:
Originally Posted by AlisonL View Post
So this means we would have to update it with a new one? No way. Not into gadgets and its not something we have to have. I got sick of it constantly "talking". I find it as annoying as a cellphone.
I am technology challenged and intend to stay that way. LOL
Generally you can install new updated data software in the GPS unit, generally at a cost.

I haven't updated mine in over 10 years...


Rich
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Old 04-22-2009, 01:16 PM
 
Location: New Mexico USA
17,453 posts, read 18,525,729 times
Reputation: 20081
Quote:
Originally Posted by collinsl View Post
I was under the impression that GPS resolution was limited to about 5M for the general public to save on satellite processing time etc, but the military could get accuracy to within 5CM
GPS was initially created by the Department of Defense, for use with military guidance and targeting systems. Saving satellite processing time was never mentioned to me as a reason for the apparent 'random' errors added to the data. This was avoided anyway with Diferential GPS units, which were being developed for some airport landing and surveyor systems. The 'random' signals were turned off, in early 2000 I believe.



Rich
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Old 04-22-2009, 01:36 PM
 
5,375 posts, read 7,030,237 times
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While I was researching this topic (okay I was Googling it), Mike0421 was writing his post above. My research was a bit less scholarly but I came up with similar results shown below, and then I'll state my own opinion about what should be done.

Technically the intersection of the four states and Four Corners Monument should be located at 37 N, -109 W. The border between Utah and Arizona or between Colorado and New Mexico is described as 37 N. The border between Colorado and Utah or between New Mexico and Arizona is described as -109 W. That would be here. (Don't get confused by the 59' 60" notation. That's just a Google display glitch. In fact 59' 60" is equal to one degree.)

First, let's discuss why the Utah/Colorado border was intended to be a straight line along the longitude, but it has a kink in it. Quoting from this article:

Quote:
Utah’s boundaries are not defined by landforms such as mountain divides or rivers. Surveyors mapped Utah’s boundaries using transit and compass, chronometer and astronomical readings, previous surveys, and interviews with residents. The boundaries were intended to run parallel to lines of latitude and longitude.

So, why the westward jog of more than one mile? In 1879 a survey to establish the western border of Colorado started at Four Corners, the only place in the USA where four states share a point, and continued on a true-north line to the southern border of Wyoming. The survey continued north about 276 miles to the Wyoming border but ended about one mile west of where they expected to intersect the Wyoming line; somewhere there was a westward jog in the border.

An 1885 survey found an error of slightly over one mile between mileposts 81and 89 (81 and 89 miles north of Four Corners), and an 1893 survey by the U.S. Coast and Geodetic Survey found a half-mile error between mileposts 100 and 110.

Why didn’t the surveyors change the boundary when they found errors? Once a boundary is marked on the ground and accepted by all interested parties it is a true line even though it doesn’t follow the written description.

A boundary between two states may be changed by agreement of the state legislatures and must be approved by Congress. The Colorado/Utah border stands as surveyed!
There's another interesting kink between Colorado and New Mexico right about here. Continued research will show you that many borders are kinkier than we ever imagined.

Okay, getting back to the main point, the articles linked in other posts earlier in this topic stated that they had discovered that according to new surveys the Four Corners Monument is in the wrong spot. Keep in mind that when the Colorado border was surveyed in 1859 they started from the Four Corners Monument and worked north. It doesn't take much imagination to conclude that when they determined where the four corners intersected they screwed up. That means that everything based upon that survey was screwed up too!

But is the Four Corners Monument really in the wrong place? Nope! Let's reread the quoted article part that I italicized: Once a boundary is marked on the ground and accepted by all interested parties it is a true line even though it doesn’t follow the written description. Four Corners is where they started from, everybody agreed on the survey results, so by definition the Four Corners Monument is exactly where the four states intersect!

This is the kind of situation when science and law conflict with one another. The intersection was intended to be at 37 N, -109 W but it ended up about a two miles away, and if somebody wants to move it there would be in endless lawsuits. The states do intersect at the monument and the monument is in the right place, but the intersection is not at 37 N, -109 W.

The Four Corners Monument will stay exactly where it is, and it is legally the correct spot for the intersection of the four states.
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Old 04-22-2009, 02:03 PM
 
Location: Denver, Colorado U.S.A.
11,020 posts, read 12,536,505 times
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I've noticed that the state lines on square states are anything but straight, if you look at the satellite view and zoom in. They're quite crooked.
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