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Details for Benchmark: AE9176

N 41° 53.433 W 091° 39.083 (NAD 83)

Altitude: 841.74

Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)

Location:
In LINN county, IA View Original Datasheet
Designation:
57 24 RESET
Marker Type:
vertical control disk
Setting:
a metal rod with base plate buried/screwed into the ground
Stability:
Mark of questionable or unknown stability.

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I was out on Good Friday searching for benchmarks in the area. Ever since "social distancing" became a thing, I have taken an interest in finding benchmarks. This was perfect weather to hunt bench marks!

I spotted the witness post but had to dig to find the benchmark. The grass had grown around it. I did a little weeding so that this benchmark can enjoy some daylight again. N 41 53.438 W 91 39.100

Good condition 7.5 ft N of a cable warning post, 7 ft N of a telephone box, 6.0 N of the face of the corner post, and 0.7 ft NNW of a witness post.

House and pole have been removed. Sky visibility good.

Note that despite being reset this is a 2nd order mark. It would appear NGS releveled through it around 1998-2002.

[Photos:]
photoAE9176-57_24_RESET-2E-20180303.jpg
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photoAE9176-57_24_RESET-1-20180310.jpg
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photoAE9176-57_24_RESET-3W-20180310.jpg
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Found in good condition bronze NGS and State Survey Vertical Control Mark 57 24 RESET 1973 RESET 1974 at handheld coordinates N41 53.437 W091 39.098. Sky visibility good.

No distance measurements were made, but it appears consistent with description except that it is NORTH not west of Wright Bros. Blvd.

It is mysterious that the disk has two reset dates stamped on it, but only 1974 is noted on the data sheet.

Note that this position is about 1/4 mile east and on the other side of the blvd from MG0571 57 24 which it seems to replace, the longest move I have seen. See also descriptions for nearby MG0569 57 25 and MG0570 57 25 RESET 1973 which have not been found.

[This entry was edited by Bill93 on Saturday, September 18, 2004 at 8:54:22 AM.]

Documented History (by the NGS)

01/01/1974 by NGS (MONUMENTED)
01/07/1998 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1998 (GAS) 0.2 KM (0.10 MI) WESTERLY ALONG DOWS STREET FROM THE POST OFFICE IN ELY, THENCE 2.2 KM (1.35 MI) NORTHERLY ALONG STATE STREET, THENCE 4.3 KM (2.65 MI) WESTERLY ALONG WRIGHT BROS BOULEVARD, 39.7 M (130.2 FT) EAST OF THE SOUTHEAST CORNER OF A HOUSE, 20.3 M (66.6 FT) WEST OF THE BOULEVARD CENTER, 20.2 M (66.3 FT) EAST OF A UTILITY POLE, 2.1 M (6.9 FT) NORTH OF A FENCE CORNER AND AN UNDERGROUND CABLE WARNING SIGN, 0.3 M (1.0 FT) NORTH OF A WITNESS POST, 0.3 M (1.0 FT) ABOVE THE LEVEL OF THE BOULEVARD, AND 0.2 M (0.7 FT) WEST OF A FENCE. NOTE--THE DISK IS ENCASED IN A 4-INCH PVC PIPE AND IS FLUSH WITH THE GROUND SURFACE.

Control Text

  • The horizontal coordinates were scaled from a topographic map and have an estimated accuracy of +/- 6 seconds.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in September 2000.
  • The geoid height was determined by GEOID99.
  • The dynamic height is computed by dividing the NAVD 88 geopotential number by the normal gravity value computed on the Geodetic Reference System of 1980 (GRS 80) ellipsoid at 45 degrees latitude (g = 980.6199 gals.).
  • The modeled gravity was interpolated from observed gravity values.

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