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Details for Benchmark: MG0090

N 41° 28.817 W 090° 20.900 (NAD 83)

Altitude: 572.61

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

Location:
In HENRY county, IL View Original Datasheet
Designation:
59.5 A
Marker Type:
survey disk
Setting:
light structures
Stability:
Mark of questionable or unknown stability.

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Found

N 41° 28.965 W 090° 20.917

Found it as described, markings were hard to read.

Documented History (by the NGS)

Unknown by IRC (MONUMENTED)
01/01/1935 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1935 AT COLONA. AT COLONA, HENRY COUNTY, ON THE CHICAGO, ROCK ISLAND AND PACIFIC RAILWAY, 10 POLES EAST OF THE STATION, 100 FEET NORTHEAST OF A BRIDGE, AT ILLINOIS-MISSISSIPPI CANAL LOCK 28, AND IN THE TOP OF THE SOUTHWEST END OF THE SOUTHEAST WALL. A DISK, STAMPED ILL MISS CANAL 59.5A.
07/17/1996 by USPSQD (MARK NOT FOUND)
RECOVERY NOTE BY US POWER SQUADRON 1996 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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