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Details for Benchmark: ME2893

N 41° 44.584 W 087° 35.646 (NAD 83)

Altitude: 587.45

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

Location:
In COOK county, IL View Original Datasheet
Designation:
AVALON
Marker Type:
triangulation station disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

Reference Points

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Documented History (by the NGS)

01/01/1977 by NGS (MONUMENTED)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1977 (JLO) THE STATION IS LOCATED IN THE SOUTH EDGE OF CHICAGO, IN THE NORTH SECTION OF AVALON CITY PARK, ABOUT 300 FEET SOUTH OF THE INTERSECTION OF EAST 83RD STREET AND SOUTH AVALON AVENUE. ADDRESS 1231 EAST 83RD STREET. STATION MARKS, STAMPED---AVALON 1977---, ARE STANDARD DISKS. THE SURFACE DISK IS SET IN THE TOP OF A 12-INCH CYLINDRICAL CONCRETE MONUMENT THAT IS 3 INCHES BELOW A CAST IRON COVER WITH THE LETTERING, NATIONAL GEODETIC SURVEY. IT IS 66 FEET NORTHWEST OF THE NORTHEAST CORNER OF A FENCE AROUND THE SWIMMING POOL AND 30 FEET SOUTHEAST OF A LIGHT POLE NUMBER W3. THE UNDERGROUND DISK IS SET IN THE TOP OF AN IRREGULAR MASS OF CONCRETE 42 INCHES BELOW THE GROUND SURFACE. REFERENCE MARK 1, STAMPED---AVALON NO 1 1977---, IS A STANDARD DISK SET IN THE TOP OF A 12-INCH CYLINDRICAL CONCRETE MONUMENT THAT IS FLUSH WITH THE GROUND SURFACE. IT IS 38 FEET NORTH OF THE NORTHWEST CORNER OF THE FENCE AROUND THE SWIMMING POOL AND 30 FEET EAST OF A 16-INCH OAK TREE. REFERENCE MARK 2, STAMPED---AVALON NO 2 1977---, IS A STANDARD DISK, SET IN THE TOP OF A 12-INCH CYLINDRICAL CONCRETE MONUMENT THAT IS 1 INCH BELOW THE GROUND SURFACE. IT IS 59 FEET SOUTHWEST OF THE SOUTHEAST CORNER OF THE PARK BUILDING AND 16 FEET NORTHEAST OF A CONCRETE BUILDING. NO SUITABLE PLACE TO ESTABLISH AN AZIMUTH MARK. NO MEASUREMENT BETWEEN THE REFERENCE MARKS DUE TO THE CONCRETE BUILDING ON LINE. HEIGHT OF LIGHT ABOVE THE STATION MARK WAS 30.6 METERS.
01/01/1977 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1977 RECOVERED IN GOOD CONDITION.
08/06/1992 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1992 IN CHICAGO, AT 1215 EAST 83RD STREET, 29.5 M (96.8 FT) SOUTH OF REFERENCE MARK 2, 27.3 M (89.6 FT) EAST OF REFERENCE MARK 1, 20.1 M (65.9 FT) NORTHWEST OF THE NORTHEAST CORNER OF A CHAIN-LINK FENCE ENCLOSING THE AVALON CITY PARK SWIMMING POOL AT 1215 EAST 83RD STREET, 13.2 M (43.3 FT) NORTH OF A FENCE, 5.3 M (17.4 FT) EAST OF THE EAST EDGE OF A BASKETBALL COURT, AND THE MONUMENT IS RECESSED 0.1 M (0.3 FT) BELOW THE GROUND SURFACE. NOTE--ACCESS TO THE MONUMENT IS THROUGH A 6-INCH SQUARE METAL COVER INSCRIBED NATIONAL GEODETIC SURVEY.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in October 1999.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in April 1995.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • 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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