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Details for Benchmark: AH7245

N 38° 39.804 W 078° 18.060 (NAD 83)

Altitude: 1717.23

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

Location:
In RAPPAHANNOCK county, VA View Original Datasheet
Designation:
UPPER METER BASE
Marker Type:
gravity station disk
Setting:
retaining walls, concrete ledge, etc.
Stability:
May hold, but of type commonly subject to surface motion.

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I made a big detour on my trip from S. Florida to Boston to visit this BM.
Concrete broken off and disk missing. Only a small indication of the hexagonal disk outline remains.
So sad! (:<

[Photos:]
photoAH7245-UPPER_METER_BASE-1-20140803
photoAH7245-UPPER_METER_BASE-3NW-20140803

Mark found as described. Haven't stopped here in years.

Found as described.
One of the most unusual disks I've ever seen.

[Photos:]
photoAH7245 - Closeup
photoAH7245 - Area View
Station is to the right of an old artesian well. I remember stopping here on vacation years ago and enjoying a cold refreshing drink. To the best of my recollection, the fountain was closed for health reasons.

The location of this unusual, hexagonal mark is adequately described by the most recent recovery note in the NGS Data Sheet.

[Photos:]
photoUPPER METER BASE -- Rappahannock County, VA

I visited this station again. The revised location discription is as follows:

The station is a hexagonal disk on a ledge on the right side of a walled-in stone and mortar springwater fountain, which is in the middle of a long retaining wall on the side of the mountain by the highway. The station is 43 feet Northwest of the centerline of Highway 211, 30 feet Southwest of the Northeast end of the retaining wall, 6 feet Northeast of the center of the walled-in fountain, and about 5 feet above the level of the highway.

It is 35 feet Northeast of bench mark F 95 RESET 1942 (HW0230).

As opposed to a 50 by 50 CM square concrete monument that is the typical setting of a gravity station, this station is set in a narrow rock and mortar ledge.

This mark was found as described.
The stamping is faint, but readable.

[Photos:]
photoAt station UPPER METER BASE in Rappahannock CtyVA
The station's location is on the small ledge indicated by the yellow arrow. There is some oddness about this location - two oddly written and different NGS descriptions only 6 months apart. The station is in a man-made rock wall full of cracks. Compounding all this is an arrow in the disk, making it look like a reference mark. The F 95 station, disk 1/3 missing was not found at all.
photoStation UPPER METER BASE in Rappahannock CtyVA
A very unusual disk. Is it truly UPPER METER BASE, or is it a reference mark to same? I logged it as the station. There is no mention of a reference mark.

Documented History (by the NGS)

Unknown by CGS (MONUMENTED)
04/15/1998 by NGS (GOOD)
DESCRIBED BY NATIONAL GEODETIC SURVEY 1998 (RWA) FROM THE US211 AND US522 INTERSECTION IN SPERRYVILLE VIRGINIA, GO WEST ON US211 5.3 MI (8.5 KM) TO THE MARK ON THE EAST END OF THE STONE SPRING. THE MARK IS IN A ROCK WALL IN THE EAST END OF THE SPRING, 13 METERS NORTH OF THE CENTERLINE OF THE HIGHWAY, 9 METER WEST OF THE A STONE RETAINING WALL BEHIND THE STATION AND 10.7 METERS EAST OF BENCH MARK F 95 RESET. THE MARK IS A OLD STANDARD NGS GRAVITY DISK STAMPED UPPER METER BASE AND SET IN A 50 BY 50 CM SQUARE CONCRETE MONUMENT.
10/02/1998 by NGS (GOOD)
RECOVERY NOTE BY NATIONAL GEODETIC SURVEY 1998 (RLA) FROM THE POST OFFICE IN SPERRYVILLE, VA. ZIP CODE 22740, ON STATE ROAD 1001 GO NORTHWEST FOR 0.2 MI (0.3 KM) TO THE JUNCTION OF US HIGHWAY 211. TURN LEFT AND GO WESTERLY ON US HIGHWAY 211 FOR 5.5 MI (8.9 KM) TO THE MARK ON THE RIGHT IN A ROCK LEDGE. IN ROCK RETAINING WALL AT SPRING IN THE EAST END 9.14 METERS (29.99 FT) WEST OF END OF ROCK WALL, 13 METERS (42.7 FT) NORTH OF CENTERLINE OF 211, 5.4 METERS (17.7 FT) SOUTH OF ROCK WALL, 10.75 METERS (35.27 FT) EAST OF BM F 95 1933 RESET 1942, DISK 1/3 MISSING. NOTE--RETAINING WALL HAS CRACK NEAR DISK. STILL STABLE.

Control Text

  • The horizontal coordinates were established by GPS observations and adjusted by the National Geodetic Survey in April 1999.
  • The orthometric height was determined by differential leveling and adjusted by the National Geodetic Survey in May 1999.
  • The X, Y, and Z were computed from the position and the ellipsoidal ht.
  • The Laplace correction was computed from DEFLEC99 derived deflections.
  • The ellipsoidal height was determined by GPS observations and is referenced to NAD 83.
  • 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.

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