Dating "UNK" strings

[kayakbird]

Hi All,

 

I did attempt a subject search, but I am not good at data base queries.

 

Yesterday afternoon it got too hot along the Big Hole River near Melrose, Montana to enjoy our quest for 1906 marks, so Okie'sKid and I headed for Elk Park north of Butte where I had noticed a series of "Alpha" "single digit" points in Jefferson County.

 

From the county line north to Boulder we found six undated brass caps, one possible tang (see RX0317 & RX0318) from either the original UNK R8 or the 1942 R8 RESET. Two of them were in quarried stone structures, two in granite posts, one in a native rock and one - a flat "U.S. COAST & GEODETIC SURVEY B. M."- was set in a concrete RR bridge abutment.

 

I would really like to know when these were set; wondering if the flat B.M. was still in general use then, or if it just happened to be in the bottom of somebody's bucket.

 

Mike

 

note posted with RX0317 & RX0318

 

WE FOUND A 5/8 COPPER TANG OR BOLT AT THIS LOCATION. THE TOP PORTION OF THE BRIDGE IS NEW, BUT THE LOWER ABUTMENT LOOKS TO BE THE ORIGINAL RR STRUCTURE.

 

THIS MARK WAS RESET IN 1942. WOULD THE BOLT/TANG IN THE PHOTOS MOST LIKELY BE FROM THE ORIGINAL (DATE UNKNOWN) DISK OR THE 1942 SETTING OR NEITHER.

[NGS Surveyor]

Mike, Here is some information about early leveling reports. The 1907 report is currently being scanned, so it is not on-line yet.

 

1900 - C&GS Report of the Superintendent 1898-1899, Appendix 8, pgs 347-886, "Precise Leveling in the United States" – http://docs.lib.noaa.gov/rescue/cgs/003_pdf/CSC-0102.PDF

 

1903 - C&GS Report of the Superintendent 1902-1903, Appendix 3, pgs 189-809, "Precise Leveling in the United States, /1900-1903, with a Readjustment of the Level Net and Resulting Elevations" - http://docs.lib.noaa.gov/rescue/cgs/004_pdf/CSC-0107.PDF

 

1907 - C&GS published in 1909, "Precise leveling in the United States 1903-1907, With A Readjustment of the Level Net and Resulting Elevations" (to be scanned)

 

1912 - C&GS Special Publication 18, "Fourth General Adjustment of the Precise level Net in the United States and the Resulting Standard Elevations" - http://docs.lib.noaa.gov/rescue/cgs_specpu...U35no181914.pdf

 

You could also check the USC&GS Annual Reports for the years that interest you, see: http://docs.lib.noaa.gov/rescue/cgs/data_r...al_reports.html

 

The flat top bench mark disks were used from c1903 to c1916, although at least one was used as late as 1932. Here is a section from my survey mark paper on early bench marks (meaning vertical control points only):

 

“Known symbols in the disk center, in approx. chronological order, include:

A. Slash (about ¾ inch long) (c1903 – c1913) One was also found from 1932,

PID = HT0568, see Figure 19.

B. Circle (about 15/16 inch in diameter) (c1907 – c1911); a convex disk with a circle in the center was found dated 1941, PID = AG1367. (Center square mentioned in 1909 and 1914, but not seen),

C. Circle with slash inside (c1916 – c1970), this disk is convex, first used for all bench marks, then after c1924 used for tidal bench marks only.

D. Three slashes, each with a cross slash about 3/16 inch long; convex disk; most common; text “BENCH MARK” upside down compared to other disks except the TRAVERSE STATION disks. See Figure 31, photo Dan Winester, NGS ; (c1923 – c1985), PID = RL1697.

E. One slash, with a cross slash about 3/16 inch long (c1957 – c1970), see Figure 32.”

 

GeorgeL

NGS

[kayakbird]

George,

 

Thanks for the links and the information.

 

Maybe I should know this, have figured it out by now or looked it up; but were the A thru Z number strings set by the US C & G Survey systematic, sequential/chronological? And by state, part of state, region of country, or any pattern at all?

 

The first 1906-1908 Precise Level Net mark in Montana is A at Monida and the last just north of the Wyoming border is H 8. There is/was a non-published I 8 just north of Butte, Silver Bow County, followed by K 8 dated 1928 (in the DATASHEET); and then L 8 and others that we found further north in Jefferson County yesterday. Further north, at Ulm, Cascade Co, SS0903 I 10 is not date stamped, but given a monumented date of 1913 in the DATASHEET.

 

Could all of yesterdays UNK's be from 1913 or did they get named or numbered or both at some other time.

 

The photos of flat B.M. disk found yesterday also seems to show a slightly different font than A 2 at Dillon, Montana and the several between Hardin, Montana and Cadiz, Wyoming.

 

Mike

[DaveD]

USC&GS/NGS level lines were generally alpha-numeric (e.g. A, B, C or B 2, C 2, D 2 etc.) by state. There are of course some occasions where this is not the case, but it was and continues to be the general rule. I have looked at the data you mentioned below, and from a brief review I think that most of the stations with dates "UNK" are part of the 1928 level line. Unfortunately, when the vertical control data was being automated for inclusion in the NGS database, some of the teams doing to description automation failed to look at the older publications to find the correct years when marks were set. As time and resources permit, I am going back and trying to fix as many of these as I can. Regrettably, since the data usually doesn't have much to do with the geodetic values it is not easy to find the resources to assist in this effort.

 

George,

 

Thanks for the links and the information.

 

Maybe I should know this, have figured it out by now or looked it up; but were the A thru Z number strings set by the US C & G Survey systematic, sequential/chronological? And by state, part of state, region of country, or any pattern at all?

 

The first 1906-1908 Precise Level Net mark in Montana is A at Monida and the last just north of the Wyoming border is H 8. There is/was a non-published I 8 just north of Butte, Silver Bow County, followed by K 8 dated 1928 (in the DATASHEET); and then L 8 and others that we found further north in Jefferson County yesterday. Further north, at Ulm, Cascade Co, SS0903 I 10 is not date stamped, but given a monumented date of 1913 in the DATASHEET.

 

Could all of yesterdays UNK's be from 1913 or did they get named or numbered or both at some other time.

 

The photos of flat B.M. disk found yesterday also seems to show a slightly different font than A 2 at Dillon, Montana and the several between Hardin, Montana and Cadiz, Wyoming.

 

Mike