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Details for Benchmark: LX5339

N 41° 18.330 W 072° 04.285 (NAD 83)

Altitude: 0

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

Location:
In NEW LONDON county, CT View Original Datasheet
Designation:
BLACK LEDGE ROCKS THAMES R ENT
Marker Type:
rock awash
Setting:
setting not listed - see description
Stability:

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Saw from ferry. you can see the water breaking over the rocks.

Documented History (by the NGS)

01/01/1947 by CGS (FIRST OBSERVED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1947 (JCS) THESE ROCKS WERE LOCATED AS DANGERS TO NAVIGATION. THEY COVER A SMALL EXTENT OF BLACK LEDGE AT THE ENTRANCE TO THE THAMES RIVER. AT MEAN HIGH WATER THEY BARE 2 FEET. THE POINT OBSERVED ON WAS THE HIGHEST ROCK NEAR THE CENTER OF THE ROCKS.
01/01/1954 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1954 (LFW) BLACK LEDGE ROCKS STILL EXIST, AND APPEAR TO BE AS DESCRIBED IN THE ORIGINAL 1947 DESCRIPTION.
01/01/1984 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1984 (BWR) ROCKS ON BLACK LEDGE RECOVERED GOOD. RECOVERED AS DESCRIBED IN 1947 DESCRIPTION.
01/01/1989 by USPSQD (GOOD)
RECOVERY NOTE BY US POWER SQUADRON 1989 (RMS) RECOVERED IN GOOD CONDITION.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in August 1998.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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