Details for Benchmark: HT1484
N 37° 19.833 W 122° 23.350 (NAD 83)
Coordinates may not be exact. Altitude is ADJUSTED and location is SCALED. (more info)
- In SAN MATEO county, CA View Original Datasheet
- R 1239
- Marker Type:
- bench mark disk
- light structures
- Mark of questionable or unknown stability.
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Documented History (by the NGS)
|01/01/1972 by NGS (MONUMENTED)
|DESCRIBED BY NATIONAL GEODETIC SURVEY 1972
10.1 MI S FROM HALF MOON BAY. 9.3 MILES SOUTH ALONG STATE HIGHWAY 1 FROM THE JUNCTION OF KELLY AVENUE AT HALF MOON BAY, THENCE 0.8 MILE SOUTH ALONG STAGE ROAD, 0.3 MILE NORTH OF THE JUNCTION OF LA HONDA ROAD AND THE SAN GREGORIO POST OFFICE, IN THE TOP OF THE SOUTHWEST CONCRETE HEAD WALL OF AN 18-INCH PIPE CULVERT, THE HEAD WALL IS 3 1/2-FEET HIGH AND 20-FEET LONG, 7.5 FEET NORTHWEST OF THE SOUTHEAST END OF THE HEAD WALL, 18 1/2 FEET SOUTHWEST OF THE CENTER LINE OF THE ROAD, 44 FEET WEST AND ACROSS THE ROAD FROM A POWER POLE WITH A GUY POLE, AND ABOUT 3 1/2 FEET HIGHER THAN THE ROAD.
|01/01/1978 by NGS (GOOD)
|RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1978
RECOVERED IN GOOD CONDITION.
- 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.