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Details for Benchmark: LC0721

N 40° 39.100 W 088° 46.700 (NAD 83)

Altitude: 740.43

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

Location:
In MCLEAN county, IL View Original Datasheet
Designation:
T 246
Marker Type:
bench mark disk
Setting:
set into the top of a round concrete monument
Stability:
May hold, but of type commonly subject to surface motion.

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Got off the interstate to get out and stretch my legs a bit. After finding a cache, I decided to also locate a benchmark. This one's still there in good condition.

[Photos:]
photoBenchmark with GPS
photoWitness post and base
photoView from old Highway 66

Still there, easy to find, and only a couple hundred yards from one of my caches. The witness post can be seen from the road.

[Photos:]
photoLC0721 (T 246)

Found this one today.

[Photos:]
photoLC0721
Near Lexington, IL

Documented History (by the NGS)

01/01/1960 by CGS (MONUMENTED)
01/01/1961 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1961 1.4 MI N FROM LEXINGTON. ABOUT 0.45 MILES WEST ALONG WEST MAIN STREET FROM THE POST OFFICE IN LEXINGTON, THENCE 1.0 MILE NORTHEAST ALONG U.S. HIGHWAY 66, AT THE JUNCTION OF AN ASPHALT PAVED ROAD SOUTH (OLD U.S. HIGHWAY 66), 100 FEET SOUTHEAST OF THE CENTERLINE OF THE NORTHBOUND LANE OF U.S. HIGHWAY 66, 306 FEET NORTHEAST OF THE CENTER OF THE JUNCTION OF U.S. HIGHWAY 66 AND OLD HIGHWAY 66, 36 FEET NORTHWEST OF THE NORTHWEST RAIL OF THE SOUTHBOUND TRACK OF THE GULF MOBILE AND OHIO RAILROAD, 9 FEET SOUTHWEST OF A GUY WIRED TELEGRAPH POLE, 2.7 FEET NORTH OF A METAL WITNESS POST, 2 FEET ABOVE THE LEVEL OF U.S. HIGHWAY 66, AND SET IN THE TOP OF A CONCRETE POST PROJECTING 2 INCHES.

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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