N 38.58778° W 78.3597°
3594 ft.
Triangulation Station Disk
Square Concrete Monument
Year Established:
Established By:
Good as of October 1, 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 survey mark has been 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.

Reference Objects
Designation Status Condition Image
THORO ERDL AZ MK 1 Not Found Unknown (Not Found)
THORO ERDL AZ MK 2 Recovered Good NGS Azimuth Mark Disk THORO ERDL AZ MK 2
THORO ERDL RM 1 Not Found Unknown (Not Found)
THORO ERDL RM 2 Recovered Good NGS Reference Mark Disk THORO ERDL RM 2