Details for Benchmark: LC0758
N 40° 50.650 W 088° 40.583 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In LIVINGSTON county, IL View Original Datasheet
- ROOKS AZ MK
- Marker Type:
- azimuth mark disk
- set into the top of a round concrete monument
- May hold, but of type commonly subject to surface motion.
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Documented History (by the NGS)
|01/01/1960 by CGS (MONUMENTED)
|01/01/1961 by NGS (GOOD)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1961
3.2 MI SW FROM PONTIAC. ABOUT 2.3 MILES SOUTHWEST ALONG U.S. HIGHWAY 66 FROM ITS JUNCTION WITH STATE HIGHWAY 116 IN THE SOUTHWEST PART OF PONTIAC, THENCE 0.9 MILES WEST ALONG A GRAVEL ROAD, AT THE JUNCTION OF A GRAVEL ROAD SOUTH, 23.5 FEET SOUTH OF THE CENTER LINE OF THE ROAD, 42 FEET EAST OF THE CENTER LINE OF A ROAD, 46 FEET SOUTHEAST OF THE CENTER OF THE ROAD JUNCTION, 1 FOOT NORTH OF THE FENCE, 1.8 FEET EAST-NORTHEAST OF A METAL WITNESS POST, 0.5 FEET BELOW THE LEVEL OF THE ROAD, AND SET IN THE TOP OF A CONCRETE POST FLUSH WITH THE GROUND.
- 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.