Back to the learning curve

[+m&h]

We may be missing something in our reading of the datasheet for ES0782, RANDELL 2, near Joseph City, AZ. This mark was set when RANDELL was threatened with destruction (which did eventually come) by I-40 construction. The mark is a Horizonal Control Mark, and has two reference marks, RM 3 and RM 4 (more on that in a moment). We can't find in the datasheet any precise information about the locations of the reference marks. Now, it's a bare hill and they're both within about 25 feet of the main station and its eight- or ten-foot witness post, so finding them is not the problem. Our question is, are the azimuths and distances from the mark to the RMs on file somewhere? They must be, right? Otherwise the RMs don't refer to much.

 

We suppose that the RMs are numbered 3 and 4 because the original mark used 1 and 2 for its RMs, which ended up with their own PIDs which at this moment are still active in the NGS database (ES0063 and ES0065). We looked diligently, did not find any trace of RM2, but found RM1 in its post yanked out of the ground. We took some pictures, posted logs, and wrote Deb, leaving to her the question whether RM2 is also destroyed.

 

By the way, the two marks nicely illustrate how a mark you can see is obviously destroyed, and one you can't is only possibly destroyed.

 

We will be grateful for learned comment on the datasheet question.

[+seventhings]

m&h -

 

I had a similar situation last week with respect to GV5086, survey disk DESHA RESET (DESHA set in 1934, the reset monumented in 1960) at the St John's Methodist Church in Essex Co., VA. The NGS datasheet has RMs 1, 2 and 3 in the boxscore, but RMs 3, 4 and 5 surround the station. DNF RM2 and did not search for RM1 (time constraint, cultivated fields and no info other than the Geod. az.)

 

Interestingly, the stamping "No. 4" and "No. 5" on those two RMs looks original (that is, not over-stamped numbers on the original disks for RMs 1 and 2), but both RM disks contain "1934" (the date of the original DESHA) as well as "1960" (the reset date). The main station has both dates, as well. RM3 has only "1934". All of the four disks are stamped "DESHA", but none of the four disks are stamped "RESET".

 

Fortunately, the two heretofore undocumented RMs 4 and 5 were close to and easily visible from the main station.

 

Will

 

see GV5086

[+m&h]

Will--

 

That’s a rich find!

 

It may be that reference marks sometimes take their stamped years from the main mark, regardless of whether they may have been set later. We recently found RM 3 for DV2061, PHOENIX BASELINE EAST, set with two reference marks in 1947. The 1962 recovery note contains the sentence “Reference Mark 3 was established at this time.” The mark is stamped “BASELINE EAST NO 3 1947.”

 

See DV2061

[+m&h]

Will--

 

P.S. Wde have not learned how to link. Just tried it, and failed. Sorry.

[NGS Surveyor]

DaveD and I just talked about station RANDELL. The “2” mark was probably established by the NGS Mark Maintenance person for Arizona (in 1980), L.W. LW’s boss was CLN, the initials on the Datasheet. Both DaveD and I know these two individuals, both of whom are now retired. The other clue is that RANDELL 2 has a third-order position. If an NGS field crew had set RANDELL 2 it would most likely have been second- or first-order. So, what happened to the directions and distances to the RMs? Well there are several possibilities: (1) someone forgot to include them when the information was keyed in, (2) since it was third-order, the data might have been purposely left out, or (3), there was no known initial azimuth so that the azimuths to RM 3 and RM 4 could not be computed. Our database person looked and the data is not in the NGS database, he said he will look in the old paper records.

 

Just before I was ready to post this, our database person showed up at my desk WITH THE MISSING INFORMATION! The data was not in the database because of a problem with the initial direction (#3 above). But I think there is enough information to get what you need. So here is the info:

 

Angle observed at RANDELL 2

Direction to RANDELL 65 deg 10min 24.5 sec

Direction to RM 4 131 deg 30min 09.5sec

Direction to RM 3 257deg 18min 50.1sec

 

Distance from RANDELL 2

To RM 4 7.340M

To RM 3 7.786M

So, you have the positions of RANDELL and RANDELL 2 (from the Datasheet) and can do an INVERSE computation between them. That will give you the azimuth from RANDELL 2 to RANDELL. Then subtract the directions above to obtain the angles from RANDELL to each RM. Then add each of these angles to the azimuth found above and you’ll have the azimuth to each of the RMs. Clear?

Good Luck!

 

I will send the same guy the information for the other station and we’ll see if he can find anything.

 

Regarding stamping on RMs, in 1968 a booklet of rules for stamping disks was written. The rule for this case required that the RMs be stamped with the date they were set. RM 3 and RM 4 were stamped in 1980 according to this rule. Of course, years earlier the rules may have been different or there may not have been any rules. This booklet is not presently on-line, but I hope to get it on the NGS www site this summer.

 

GeorgeL

NGS

[+m&h]

George--

 

Bravo! Magnificent. Many thanks to you and your database person.

 

Cheers,

[+m&h]

George--

 

RM4 2590805.84

RM3 0245646.44

 

Our hasty pocket compass readings were RM 4 246, RM 3 10. Rough, but within a couple of degrees. We’re very grateful for the chance to play with the information you provided.

 

Cheers,