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Bill93

Triangulation station mystery

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I'm interested in LE0511 (GC link) (NGS link) because my sister is moving to that neighborhood and it would be a good puzzle to work on while visiting there.

 

Reference marks 1 and 2 are reported as destroyed, with RM3 and 4 set in 1969. There is to-reach for the new RMs but no bearing or distance from the RMs to the buried triangulation station on the data sheet. It makes the buried station a little hard to find. I haven't looked yet, but have doubts about the old fences being there.

 

Would somebody at NGS be able to find bearing and distance in records that didn't make it to the data sheet? Or maybe I shouldn't bother them - do they really care about tri stations these days?

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I'm interested in LE0511 (GC link) (NGS link) because my sister is moving to that neighborhood and it would be a good puzzle to work on while visiting there.

 

Reference marks 1 and 2 are reported as destroyed, with RM3 and 4 set in 1969. There is to-reach for the new RMs but no bearing or distance from the RMs to the buried triangulation station on the data sheet. It makes the buried station a little hard to find. I haven't looked yet, but have doubts about the old fences being there.

 

Would somebody at NGS be able to find bearing and distance in records that didn't make it to the data sheet? Or maybe I shouldn't bother them - do they really care about tri stations these days?

 

Bill93,

 

On the 5 Sept 2012 Google Earth it looks like the northern most track are gone - maybe you will be lucky and find the reference mark witness posts. Did a bunch of scaling off the above GE and came up with 40D 42'33.31" -93D 21'43.73" for RM 3, and 40D 42'33.2" -93D 21'46.22" for RM 4. These would be bearing/distance from the Station of 130D 161.5ft and 213D 121.5ft respectively.

 

Gotta go chase birds right now - will try to post a GE image with a note on the Geocache page later this afternoon. kayakbird

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This looks like a fun one to find, especially since the mark is 18" below the surface. It looks like you've already visited the old railroad tracks in the treeline back in 2006.

I've added the Property Appraisal pic linked to BM page log. It looks like lots 7 & 8 belong to the neighbors to the west, The Jennings.

Funny, the property lines don't back-up to eachother on this image. Who owns the property between the property lines? Maybe properties in IA have easements between properties?

 

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Post some good pics when you find it!

Edited by Gungadoy

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I think the town was platted with lots, alleys, and streets that were never developed as originally expected. People on this end of town now own multiple lots and there is no visible evidence that the N-S streets were ever built.

 

You guys are thorough investigators to dig that deeply, or else totally bored and needed a diversion ;-)

 

Yes, there was a set of tracks when I took a quick look (certainly not thorough) for the elevation bench mark, with trees growing up between the rails. The north rail may not have moved much since the description was written. I'll see if I can get my brother's opinion on the age and location stability, because he used to do track maintenance and inspection.

 

It'll take a very good estimate of position to find the buried disk, with 18 inches to probe and dig. I'm probably not up to probing much area that deep unless the ground is very soggy.

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Hopefully you'll find a nice depression in the ground to ease the search!

Does anyone know, will a good or very good metal detector locate a disk 18" below the surface? Somehow I doubt my economy detector will do it.

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I read somewhere that a metal detector will find something about as deep as the coil diameter, so if you have a detector similar to mine you can go about 4 inches deep, or possibly less. I was looking for a mark that was under about 4 inches of dirt recently and failed--I had to dig until it was only about 2 inches deep.

 

A long time ago I managed to find a mark 18 inches deep by measuring carefully and repeatedly from the reference marks. I was helped by very soft soil, but also was very lucky in that I hit the buried mark without digging a wide hole. The mark had pieces of chain on top of it for detectors that work better with iron. However, there was no mention of that in the description. Cherry Hill

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