Slightly unusual setting

[Bill93]

Yesterday I found LE0442. The unusual thing was how far off center the disk was in the concrete post.

 

Then I think I found a reference mark, but it had fallen victim to a trencher and was broken, 12 feet from where it was supposed to be. I had never seen the underside of the cast aluminum disks, so this was interesting.

 

 

It has the shape of other 1970's aluminum disks I have seen, but it was corroded so badly that I can't read any cast or stamped lettering on it to confirm the identification.

 

Edit: here's a similar disk

Edited September 17, 2009 by Bill93

[AZcachemeister]

I can't help but wonder if some portion of the monument for the station mark has been broken away.

 

That 'thing' is the usual type of aluminum disk in your area? Never seen anything like that in AZ!

Honestly it looks like part of a potato-masher!

[Difficult Run]

I would say the item you found was not the reference mark. It appears to be made of zinc. Here's my logic:

 

• Color and appearance is consistent with other zinc objects I've dug with my metal detector.

(If you've dug a newer zinc penny or an old mason jar lid, you'll know what I mean).

• There is a distinct seam running through the center of the 'disk', (looks like a piece of cast machinery).

• There's a clear seam still present all the way around the rim, (yet no stamping or other cast lettering can be seen).

• I see no evidence of concrete attached to this item.

• Other aluminum disks I've found don't have this amount of corrosion.

 

In all likelihood, the item is probably a piece of broken farm machinery. However I can understand your conclusion.

 

Regarding the main station setting. The datasheet says it was set in the top of a 12 inch cylindrical monument. - Your photo shows it to be square.

 

Let us know if you find out anything more about this mark.

~ Mitch ~

[+Growf]

Regarding the main station setting. The datasheet says it was set in the top of a 12 inch cylindrical monument. - Your photo shows it to be square.

I haven't done that much benchmarking yet, but I've found the "cylindrical monument" descriptions to not be reliable. Though the posted pic doesn't show it, JZ0985 was set in a a monument that was akin to a flattened obelisk or flattened pyramid, but 1) the Groundspeak page says "Setting: set into the top of a round concrete monument", while 2) the original datasheet says "SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT" (no mention of shape). Ditto for JZ0898 and JZ0740.

 

I think Groundspeak, when importing the NGS database, took the liberty of translating any mark with "SETTING: 7 = SET IN TOP OF CONCRETE MONUMENT" into "Setting: set into the top of a round concrete monument".

Edited September 18, 2009 by Growf

[2oldfarts (the rockhounders)]

LE0442

 

Perhaps some of the winning contestants from previous benchmark hunting contests will understand the significance of this benchmark.

 

John

 

We will reveal the significance through PM or e-mail only!

[andylphoto]

 

Regarding the main station setting. The datasheet says it was set in the top of a 12 inch cylindrical monument. - Your photo shows it to be square.

 

 

Actually, I think I'll agree with AZcachmeister. To me, this looks like a 12-inch cylindrical monument--the top, left and bottom all appear to be curved, with spacing on these three sides that would appear to be consistent with a 12-inch cylindrical monument. I think it looks like it's been struck by some type of equipment which broke off the right side of the setting.

 

I won't take a position on the RM. It does certainly appear to be the shape of the other RM disc you posted a photo of, and what are the chances of finding something of the same size and shape? On the other hand, it seems hard to believe that none of the lettering, including the cast lettering would be visible, while the surface remains so flat. A badly corroded surface I would expect to see more pitted, like the center area. Hard to tell from pictures though.

[Bill93]

Obviously, I'm going to have to go back to that one next chance I get. It's 2 hours from home, and slightly out of the way on the trip to visit Mom in the home town.

 

The "thing" does measure almost exactly 4 inches in diameter as called for. Maybe George can help us with whether the shape of the bottom is what it should be. His paper, however, does not show any examples of disks with large fins for embedding in concrete, and his Figure 82 shows the RM disk as having a larger diameter hump.

Edited September 18, 2009 by Bill93

[+TheBeanTeam]

Obviously, I'm going to have to go back to that one next chance I get. It's 2 hours from home, and slightly out of the way on the trip to visit Mom in the home town.

 

The "thing" does measure almost exactly 4 inches in diameter as called for. Maybe George can help us with whether the shape of the bottom is what it should be. His paper, however, does not show any examples of disks with large fins for embedding in concrete, and his Figure 82 shows the RM disk as having a larger diameter hump.

 

That is one great reference. Imagine my surprise as I am reading along and come across a few photos of mine.java script:emoticon

 

Then I remembered the thread where I gave permission for them to be used. Very cool. In the credits I misidentified as Chester Perkins though.

java script:emoticon

 

Anyhow, I hadn't seen this and am glad you linked to it.

 

And now back to your regularly scheduled potato masher topic.

 

Personally I think it could be the RM in question but damaged due to a chemical reaction or something.

 

Bill93's request for an assessment from George is a great idea. If anyone would know it would be him I would guess.

Edited September 18, 2009 by TheBeanTeam

[MarkSetter]

I believe what you found is the bottom part of one of these type of markers:

 

 

The disk is at the top and the rest of the marker would have been surrounded by concrete. Makes for a stable monument and the disk is not so easy to pop off for those that would tamper with it.

Edited September 19, 2009 by MarkSetter

[Bill93]

Bingo! We have a winner!

 

It matches that picture very well, even to the radial lines on one of the fins where for some reason it is thicker than the rest.

 

Examining the link for the picture, I tracked it back to the Berntsen catalog page for a type W1ALC.

 

So if I found the bottom piece, that is pretty strong evidence the top is disturbed.

[MarkSetter]

Bingo! We have a winner!

 

It matches that picture very well, even to the radial lines on one of the fins where for some reason it is thicker than the rest.

 

Examining the link for the picture, I tracked it back to the Berntsen catalog page for a type W1ALC.

 

So if I found the bottom piece, that is pretty strong evidence the top is disturbed.

 

Berntsen's description indicated that they were originally desgined to be set in roadways or without concrete, in the ground. However, I've set these types before within concrete and it makes it very difficult to distrub the disk without disturbing the entire monument. Of course, bulldozers or tractors can easily blow that idea out of the water.

Edited September 20, 2009 by MarkSetter

[NGS Surveyor]

I believe that MarkSetter is correct. That type of mark is what I thought of when I saw the wide “fins”. I looked back at my hard drive folder containing the original photos of the NGS aluminum disks and found photos of the back of the disks. Neither looks like the item in question. One of the NGS aluminum disks has a collar/tube for mounting on a ~3” pipe and the other has a short tube on the back with treads on the inside for mounting on an ~1” pipe. I asked another NGS person and neither of us recall NGS ever using the type of marks in MarkSetter’s post.

 

Thanks for the + comments on my survey mark paper. I hope everyone has a chance to review it. If anyone finds any errors please send me the corrections, there will be an update since I’ve already found a few minor corrections.

 

GeorgeL

NGS

[MarkSetter]

I believe that MarkSetter is correct. That type of mark is what I thought of when I saw the wide “fins”. I looked back at my hard drive folder containing the original photos of the NGS aluminum disks and found photos of the back of the disks. Neither looks like the item in question. One of the NGS aluminum disks has a collar/tube for mounting on a ~3” pipe and the other has a short tube on the back with treads on the inside for mounting on an ~1” pipe. I asked another NGS person and neither of us recall NGS ever using the type of marks in MarkSetter’s post.

 

Thanks for the + comments on my survey mark paper. I hope everyone has a chance to review it. If anyone finds any errors please send me the corrections, there will be an update since I’ve already found a few minor corrections.

 

GeorgeL

NGS

 

I've never set this type either for NGS, but I have set them for some municipalities and for some utility companies for their own control networks.

[Papa-Bear-NYC]

So are we saying that the object pictured is not a misplaced reference Mark (RM7), but rather some local survey mark which was knocked over? And RM7 is still not accounted for? Yes?

Edited September 22, 2009 by Papa-Bear-NYC

[Bill93]

I now believe this was what was set for RM6 and RM7, and the rural water people's trencher took it out. Note that the description does NOT say the RMs were in concrete, but describes them as "4 inch cast aluminum reference marks" and the piece I found is 4 inches in diameter. The longer piece with the disk could be in the bottom of their trench too deep for my metal detector, or they could have thrown it on the truck.

 

I was there again yesterday, did a more thorough sweep with the metal detector, and found only a pop can, an iron bolt, and an unrelated tag.