Details for Benchmark: LX5339
N 41° 18.330 W 072° 04.285 (NAD 83)
Coordinates may not be exact. Altitude is UNKNOWN and location is ADJUSTED. (more info)
- In NEW LONDON county, CT View Original Datasheet
- BLACK LEDGE ROCKS THAMES R ENT
- Marker Type:
- rock awash
- setting not listed - see description
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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.
- 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.