I did return, this time bringing along Rich, plenty of measuring equipment and almost a year's worth of benchmark hunting experience. But we still didn't find the mark. Rich and I carefully measured out the given distances, and the measurements placed me right on top of a particular rock that I soon found out had already been claimed by thousands of red ants. But there was no mark to be found. It's possible the disk is located beneath the boulder (which we realize now we should've moved) or the pile of soil and sand adjacent to it. We'll have to try again!
This log is meant to indicate a probable work in progress. I attempted to locate this second order vertical control station with the assistance of Zhanna, who was here at a much earlier date and was unable to find it during her visit. Unfortunately, even after measuring out the appropriate distances as given in the historical description we were not able to pin down the mark's location. The suspected area is overgrown with tall, thick weeds, and there is a dirt pile in the immediate vicinity next to a beach ball-sized boulder, either of which might possibly be covering the mark. We probed the ground quite thoroughly within a 6-foot diameter circle. I hope to return at some future time to continue the search. Perhaps someone else will have better luck in the meantime. ~Rich in NEPA~