A photo of the entire rock might help, It resembles drill hole maps that I have seen, Lower left corner small drill hole, deep to shallow ( dime size shallow indention ) direction, Lines = 5 ? I would go at least 1/2 mile and look for other trail markers. Start reading the map at the upside down V, there appears to be small symbols between the turkey tracks, there looks to be 5 symbols small drill hole and upside down V 3 turkey track = 5, the start marker may be a V shaped rock sticking out of the ground, It looks as if the rock has been turned over or we may be looking at the bottom side. All of this just a guess on my part