HHmmm, not a direct response to your question :
In this same valley I just mentioned there was a large WHITE bolder setting out in the grass. Snow like white which does not occur in this area. On that rock was a bolo chizel cut about 3 inches long. Vertical. It pointed in the direction of a diagonal line between to ancient acacia trees. We ran a cable between the two trees, took a direct strile from this white boulder to the cable and then figured down the length of the cut mark. The site dowsed to be real by two dowsers.
Now the weird part. This rock is naturally white and does not belong in the area. That is what caught my first attention. Upon close examine I found the cut mark. When we returned a month later. The white rock was gone. That is it was not a very dark brown rock. So dark I did not recognize it and at first thought someone had taken the rock.
How it turned white I have no clue.
Z