THORO ERDL (HW3272)

NGS datasheet » Geocaching.com benchmark page » Daily write-up »

State: VA
County: Madison
Quad: Old Rag Mtn
Location: N 38° 35.267' W078° 21.582'
Elevation: 3594 ft.
Designation: THORO ERDL 1959
Setting: Round Concrete Monument
Type: Triangulation Station
Year: 1959
Established By: NGS
Recovered: 01 October 2006

We were already well into our benchmark-hunting day when we stopped at the Thorofare Mountain Overlook just before noon to search for this tri-station and associated marks. Our first stop of the day had been Pinnacles Overlook, where we found the drill hole that had once held AZ MK 1, but unfortunately discovered no sign of the disk itself.

Reaching Thorofare Mountain Overlook about an hour and a half later, we first spotted RM 2 just about a yard east (not west, as stated in the description) of the guard wall. Using the reference mark and our coordinates from the datasheet, we were able to pinpoint the location of the station disk, even though it was hidden from view by a thick layer of wet grass. Rich probed the around with his hiking pole and immediately struck the monument.

With the station and RM 2 located, we set off to find RM 1. Here, we had no luck; no concrete slab was found anywhere in the vicinity. The mark may have been removed along with the slab, or simply paved over.

We then walked south about 500 feet along Skyline Drive to find AZ MK 2. (This mark is described under AI5756.)

A report on the condition of this station and associated marks was submitted to NGS, along with the following recovery note:

The station and AZ MK 2 (AI5756) were found in good condition as described.

RM 2 was found in good condition, but is about 3 feet east, not west, of the rock guard wall. Handheld GPS WAAS-corrected coordinates for RM 2 are 38 35 16.3(N) 078 21 35.0(W).

RM 1 was searched for but not found. There is no visible concrete slab near the rock guard wall.

AZ MK 1 was not found, though a drill hole is evident in outcropping bedrock situated as described at Pinnacle Overlook. It is likely this drill hole once held AZ MK 1.

Zhanna

NGS Official Description, 1959 (see datasheet for recent updates) :

DESCRIBED BY COAST AND GEODETIC SURVEY 1959 (HRL) STATION IS LOCATED ABOUT 7 MILES EAST OF LURAY AND 9 MILES SOUTHWEST OF SPERRYVILLE. ON SKYLINE DRIVE AT THOROFARE MOUNTAIN OVERLOOK. IT IS 24 FEET SOUTH OF THE NORTH CORNER OF A ROCK WALL, 54 FEET NORTH OF A THREE-FOOT OAK TREE, 3 FEET EAST OF A STONE WALL, AND 91 FEET EAST OF THE CENTERLINE OF SKYLINE DRIVE. THE MARK, A STANDARD TRIANGULATION DISC THAT IS STAMPED, THORO ERDL 1959, IS SET IN A 12 BY 12 INCH CONCRETE POST THAT PROJECTS ABOUT 4 INCHES. THE STATION MAY BE REACHED FROM THE JUNCTION OF U.S. HIGHWAY 211 AND SKYLINE DRIVE AT THORNTON GAP BY GOING SOUTH ON SKYLINE DRIVE FOR 3.9 MILES TO AZIMUTH MARK NO. 1 ON THE LEFT AT PINNACLE OVERLOOK. CONTINUE SOUTHERLY ON SKYLINE DRIVE FOR 5.85 MILES TO THE STATION SITE ON THE LEFT AS DESCRIBED ABOVE. REFERENCE MARK NO. 1 IS A STANDARD REFERENCE MARK DISC STAMPED, THORO ERDL NO 1 1959, IS SET IN A DRILL HOLE IN THE NORTHEAST CORNER OF A 2 BY 2 FOOT CONCRETE SLAB WHICH IS ABOUT 3 FOOT WEST OF THE ROCK GUARD WALL ON A WIDE BERM. AZIMUTH MARK NO. 2 IS ABOUT 500 FEET SOUTHWEST OF THE STATION, ON THE SOUTHSIDE OF SKYLINE DRIVE AND IS SET IN A DRILL HOLE IN OUTCROPPING BEDROCK. THE STANDARD AZIMUTH MARK DISC IS STAMPED, THORO ERDL 1959. REFERENCE MARK NO. 2 IS ABOUT 3 FEET WEST OF THE GUARD WALL ON THE WIDE BERM. IT IS SET IN A 12 BY 12 INCH CONCRETE POST THAT PROJECTS ABOUT 4 INCHES AND THE STANDARD REFERENCE DISC IS STAMPED, THORO ERDL NO 2 1959. AZIMUTH MARK NO. 1 IS ABOUT 1-1/2 MILE NORTHEAST OF THE STATION AT PINNACLE OVERLOOK. THE MARK, A STANDARD AZIMUTH MARK DISC, IS SET IN A DRILL HOLE IN OUTCROPPING BEDROCK, LOCATED IN THE SMALL ISLAND BETWEEN SKYLINE DRIVE AND THE ROCK GUARD WALL. THE DISC IS STAMPED, THORO ERDL 1959. HEIGHT OF LIGHT ABOVE STATION MARK 1 METERS.