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Details for Benchmark: HV3866

N 38° 54.669 W 077° 06.043 (NAD 83)

Altitude: 3

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

Location:
In ARLINGTON county, VA View Original Datasheet
Designation:
ROCK 2
Marker Type:
triangulation station disk
Setting:
in rock outcrop
Stability:

Reference Points

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Station found, unstamped per description. Mark is solid and in good condition.
All reference marks were recovered except HV3841/Rock 1.
No measurements made to reference marks due to the abundance of briars and vines in the area.

It is interesting to note that HV3841/Rock 1 was not found, despite being about 2 feet away.

RM1 no longer points to station and has shifted direction by about 80 degrees to the east.

Ruins of nearby stone hut from 1925 are still in evidence.
Photos of these ruins are posted at:
http://www.geocaching.com/mark/details.aspx?PID=HV3841

Closest vehicular access is at the end of North Kenmore Street, an entrance to Windy Run Park,
which is about 1 mile walking distance.

[This entry was edited by Difficult Run on Saturday, March 31, 2007 at 11:27:18 AM.]

[Photos:]
photoCloseup of Station
photoStation Overview
photoStation and Rowing Crew on Potomac River
photoCloseup of RM1
photoView of RM1 and Station
RM1 is in foreground. Station located in background near red backpack.

Documented History (by the NGS)

01/01/1935 by CGS (MONUMENTED)
DESCRIBED BY COAST AND GEODETIC SURVEY 1935 (JHB) THIS STATION WAS ESTABLISHED WHEN THE BUILDING PARTY FAILED TO RECOVER ROCK. ROCK WAS LATER RECOVERED BY THE OBSERVING PARTY. IT IS MARKED BY A U.S. ENGINEERS DISK, WHILE ROCK 2 IS MARKED BY A STANDARD U.S.C. AND G.S. DISK UNSTAMPED. ROCK 2 DISK WAS CEMENTED IN THE DRILL HOLE THAT SERVED AS WITNESS MARK FOR ROCK. IT IS ON A ROCK LEDGE ON THE VIRGINIA SIDE OF THE POTOMAC RIVER, ALMOST W OF THE TWIN RESERVOIRS, ABOUT 50 METERS S OF A ROCK QUARRY NOW BEING WORKED, WITH A LOW STONE HUT DIRECTLY ABOVE IT, AND THE PATH ABOUT 5 METERS ABOVE IT, THE MARK BEING NEAR THE HIGH-WATER LINE. IT IS ABOUT 15 INCHES ABOVE ROCK. ROCK REFERENCE MARK NO. 1 IS A STANDARD REFERENCE MARK SET IN A LARGE BOULDER ON THE OPPOSITE SIDE OF THE PATH AND ABOUT 2 METERS HIGHER. REFERENCE MARK NO. 2 IS A BOLT SET IN A BOULDER AT THE WATERS EDGE. ROCK IS A U.S.E.D. DISK CEMENTED IN A DRILL HOLE IN THE SAME LEDGE WITH ROCK 2. A 4-FOOT STAND WAS USED.
01/01/1946 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1946 (JMN) REFERENCE MARK 1 HAS BEEN MOVED TOWARD RIVER, PROBABLY DUE TO A LANDSLIDE. OTHERWISE, AS DESCRIBED AND IN GOOD CONDITION.
01/01/1946 by CGS (GOOD)
RECOVERY NOTE BY COAST AND GEODETIC SURVEY 1946 (RCB) THE STATION WAS RECOVERED AS DESCRIBED AND ALL MARKS WERE FOUND TO BE IN GOOD CONDITION, EXCEPT THAT R.M. 2 WAS NOT RECOVERED. A COMPLETE NEW DESCRIPTION FOLLOWS--THE STATION IS LOCATED ON THE VIRGINIA SIDE OF THE POTOMAC ALMOST DIRECTLY ACROSS THE RIVER FROM THE N END OF THE TWIN RESERVOIRS. THE ROCK QUARRY MENTIONED IN THE OLD DESCRIPTION IS NOW ABANDONED AND OVERGROWN AND THE STONE HUT NEAR THE STATION HAS BEEN DESTROYED. THE DISK AND THE STONE HUT NEAR THE STATION HAS BEEN DESTROYED. THE DISK IS ON THE POINT OF A BOULDER AT THE WATERS EDGE AND IS UNSTAMPED. REFERENCE MARK 1 IS 33.20 FEET SW OF THE STATION. THE DISK IS UNSTAMPED AND ALSO SERVES AS A REFERENCE MARK FOR D.C. - VA. BOUNDARY WITNESS MARK NO. 3. DISK IS CEMENTED IN A DRILL HOLE IN A BOULDER NEAR THE WATERS EDGE. A TRAVERSE CONNECTION WAS MADE FROM ROCK 2 TO D.C. - VA. BOUNDARY WITNESS MARK NO. 3 AND THE DISTANCE WAS FOUND TO BE 8.805 METERS.
01/01/1974 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1974 (GWJ) RECOVERED AS DESCRIBED.

Control Text

  • The horizontal coordinates were established by classical geodetic methods and adjusted by the National Geodetic Survey in November 1994.
  • The orthometric height was scaled from a topographic map.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The geoid height was determined by GEOID99.

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