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Details for Benchmark: JS4151

N 38° 45.120 W 121° 18.199 (NAD 83)

Altitude: 0

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

Location:
In PLACER county, CA View Original Datasheet
Designation:
SAN FRAN SALT LK CTY AWY BCN 8
Marker Type:
NGS Benchmark
Setting:
setting not listed - see description
Stability:

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These Airway Beacons were obsolete by the start of WWII and most of them were dismantled so the steel in the towers could be used in the war effort. They were only 60 feet tall and the beacon at the top of the tower (the actual survey mark) was 24 inches in diameter.

School construction has wiped out any traces of this installation and the NOAA/USGS database now reports this mark as "Destroyed".

Well according to the Official History, the base containing the benchmark is long destroyed. :-(

~twm3

Documented History (by the NGS)

Unknown by (MONUMENTED)
01/01/1952 by USGS (MONUMENTED)
DESCRIBED BY US GEOLOGICAL SURVEY 1952 STEEL TOWER NO LONGER EXISTS, CONCRETE BASE IS STILL IN PLACE.
01/01/1973 by NGS (MONUMENTED)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1973 (CLN) THE BEACON TOWER CONCRETE BASE HAS BEEN REMOVED. AIRLINE DISTANCE AND DIRECTION FROM NEAREST TOWN--1 MILE WNW OF ROSEVILLE

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in March 1994. The horizontal coordinates are valid at the epoch date displayed above. The epoch date for horizontal control is a decimal equivalence of Year/Month/Day.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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