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Details for Benchmark: MG0020

N 41° 30.983 W 090° 25.733 (NAD 83)

Altitude: 587.48

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

Location:
In ROCK ISLAND county, IL View Original Datasheet
Designation:
U 52
Marker Type:
bench mark disk
Setting:
massive structures
Stability:
Probably hold position/elevation well.

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Documented History (by the NGS)

01/01/1934 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1934 0.8 MI W FROM SILVIS. 0.8 MILE WEST ALONG THE CHICAGO, ROCK ISLAND AND PACIFIC RAILWAY FROM THE STATION AT SILVIS, ROCK ISLAND COUNTY, 150 FEET WEST OF THE CENTER OF THE CROSSING OF 17TH STREET, AT A BRIDGE, IN THE TOP OF THE SOUTH END OF THE WEST CONCRETE ABUTMENT, AND ABOUT 1-1/2 FEET LOWER THAN THE TRACK. A STANDARD DISK, STAMPED U 52 1934.
01/19/1988 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1988 (JEB) MARK NOT FOUND.
08/16/1996 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1996 MARK NOT FOUND.
06/05/1997 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1997 MARK NOT FOUND.

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 June 1991.
  • 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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