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Probably Slightly Eccentric...


Kewaneh & Shark
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Doing some project research today and found that GU0681 is adjacent to our project site. As I read the descriptions, it became aparent that this mark has had a busy life.

 

It's a standard triangulation station set in 1943 with a surface and underground marks, two RMs and and azimuth mark. By 1949 the azimuth mark had been destroyed and a replacement cap (reset) had been received by the California Department of Public Works. By 1952 the azimuth mark had been destroyed again, or had not been reset. In 1956 the USGS found the station had been destroyed. In 1964 & 1965 the station and RMs were found by the CGS & BOR. By 1970 both RMs had been destroyed and reset. Then in 1981 the station was found in 'EXCELLENT' condition.

 

From good to bad to excellent doesn't happen very often.

 

I thought it was funny that the elevation given in 1943 was 'ABOUT 150 FEET'. 'About' is pretty vague for a monument that is now recognized as have a first order vertical measurement. (I know that this mark was not intended to have a vertical measurement. This one just got one anyway.)

 

I think the part of the description that made me laugh the most was the reason why the underground mark is 'PROBABLY SLIGHTLY ECCENTRIC'... 'YOUTHFUL VANDALS TAMPERED WITH THE STATION MARK BEFORE THE CONCRETE HAD SET'.

 

I am looking forward to finding whatever is out there.

 

- Kewaneh

Edited by Kewaneh & Shark
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You Eccentrically recover most masts,water tanks,beacons, and church spire etc,by these type observations anyway.

 

Geo, what are those types of things used for anyway? The elevation is not exact, nor is the horizontal location. What good are they?

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Geo, what are those types of things used for anyway? The elevation is not exact, nor is the horizontal location. What good are they?

Depending on the accuracy required, they may be "good enough".

 

The nice thing about those kinds of points is that they are high enough you can sit in one spot and take your measurements without having to send a light man out to a regular mark. Just like everything else, time and money are a factor in survey work too. They may also serve as a "reality check" for more accurate surveys.

 

I can think of lots of ways they can be useful.

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Gecko,

But if they are eccentric, what are you actually measuring? Are you using them as triangulation points against known elevations so their actual elevation is unnecessary? If that is the case there is no reason for them to be benchmarks--any high structure could serve.

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Are you using them as triangulation points against known elevations so their actual elevation is unnecessary? If that is the case there is no reason for them to be benchmarks--any high structure could serve.

I believe they are "benchmarks" only in the very general sense we at Geocaching.com call all survey control marks "benchmarks". Not to be confused with what real surveyors call a bench mark which is a vertical control station (elevation).

 

As far as I know they are usually only used for horizontal control, so there is no elevation involved.

 

And while you could use any set of high points, it's nicer to use high ports that someone else has already determined their position. Otherwise you'd have to go out and take 2 to 3 other measurements from known horizontal survey points for each of the landmarks you used to figure that out.

Edited by GeckoGeek
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