Another Confusing NGS Data Sheet

[BeachBum22]

Bumped into this while looking at the photo gallery. SC2659

 

I think what has been logged twice is RM 1, not SC2659, judging from the "1" on the picture, and the text that references RM 1 as being set in a sidewalk curb (not an 8" concrete pipe) which is verified by another picture of a sidewalk.

 

If you read the text of the NGS sheet, it says that in 1958 the station was destroyed and the disc was mailed back to the NGS.

 

Question is, if the station is gone, why is the data sheet not gone too?

 

Are the reference markers of any use to a surveyor even though the main mark is gone?

 

BeachBum22

http://www.benchmarkhunting.com

Just because I can't find it doesn't mean it's not really there.

[Z15]

quote:

---

Are the reference markers of any use to a surveyor even though the main mark is gone?

---

 

Yes, its possible the RM monument can be used for a Bench Mark in the future. If the sky is open we might use it for a new GPS station etc.

 

As has been said it the past, just because a station is lost does not mean that the data sheet does not contain some data that would be of benefit to a Surveyor or someone else. A survey mark is a survey mark, weather found, not found or destroyed. It does not cease to be one if its destroyed. Its records will remain and not tossed out just because its destroyed. Mark is gone but its position may be useful for historic purposes.

 

Mike

Survey Tech (Retired)

[+Kewaneh & Shark]

Your assumption is correct about the disk shown in the photos; it is in fact Reference Monument No. 1 and not triangulation station 'WISK'. Stations such as 'WISK' traditionally have a small triangle stamped in the center of them and the reference monuments are identified by the arrow which points toward the true station. The 'found' reports also document that mark as RM#1. In 1940 the station and RM#1 were described as '...STATION IS MARKED WITH A STANDARD DISK IN THE TOP OF AN 8-INCH CONCRETE PIPE FILLED WITH CEMENT AND SET FLUSH WITH THE GROUND. THE DISK IS STAMPED WISK 1940. REFERENCE MARK NO.1 IS NE OF THE STATION, A STANDARD BRONZE DISK SET ON THE SIDEWALK CURB. THE DISK IS STAMPED WISK 1-1940.' Those descriptions have been carried on in subsequent reports.

 

To add to ElCamino's answers to your questions: another reason that the data sheet remains after the Station is destroyed is because that data sheet is also the data sheet for the two reference monuments. If the data sheet is removed, the reference monuments are effectively orphaned and rendered useless. The data sheet also mentions five other reference stations within a few miles of station 'WISK' which are a good historical reference.

 

Keep on Caching! (and Benchmarking!)

- Kewaneh

[Wild T2]

With the info on the datasheet and the NGS program "FORWARD" from the geodetic took kit on their web page you can caluclate the latitude and longitude of the reference mark.

 

Output from FORWARD

 

Ellipsoid : GRS80 / WGS84 (NAD83)

Equatorial axis, a = 6378137.0000

Polar axis, b = 6356752.3141

Inverse flattening, 1/f = 298.25722210088

 

First Station : Wisk

----------------

LAT = 46 59 7.64149 North

LON = 123 49 29.15546 West

 

Second Station : WISK RM 1

----------------

LAT = 46 59 8.01885 North

LON = 123 49 29.24593 West

 

Forward azimuth FAZ = 350 41 0.0000 From North

Back azimuth BAZ = 170 40 59.9339 From North

Ellipsoidal distance S = 11.8090 m

[+Stump]

quote:

---

I think what has been logged twice is RM 1, not SC2659

---

 

As the second "finder" of this benchmark I agree that it was indeed RM1 that was found. I wasn't thrilled about "finding" it but since it was already found and was still listed as a benchmark I logged it as found.

 

Question I guess is what should be done with this? Should it be logged as destroyed? Does it really matter since the benchmark was destroyed? After all, this is just a game and we're not actually using them for surveying.

 

Another question. Does logging a benchmark as destroyed reduce the number left to find on the benchmark page of geocaching.com? We have a number of destroyed benchmarks in our little city and I'd like to think that logging them as destroyed is accomplishing something.

[+GeckoGeek]

quote:

---

Originally posted by gaviidae:

Question I guess is what should be done with this? Should it be logged as destroyed? Does it really matter since the benchmark was destroyed?

---

I'd like to hear from DaveD what the NGS view is. I suppose if the information relating the BM/TS and RM is high accuracy, then it's still useful. But if it's only approximate, it's lost it's value. But again, I'd like to hear Dave's viewpoint.

[Dan Vull]

Good posts. There are many reasons for a data sheet to outlive certain rms. One could be that the station itself is still valid along with any surviving rms and the odd azimuth mark. The az mark could be something unrecoverable but still visible such as a church steeple, radio beacon light or what not. These are help still if a surveyor can find two other trig stations in the area for a check angle. Then there is the USC&GS habit of never throwing anything away.

Cheers,

Pat