You could be right, I thought also about this, but white tends i have seen only in Sahara where are not trees for cover. I can't remenber to see a white tend anywhere at the our local camping stores. Usually are two colors made or one of prominent colour to can be distinguished in the field. And somebody who knows the region, would knew how little above that spot which is almost in the wash, is the place of Chuck Aylor's camp which provide a clean flat region , a fire ring and water.
Whatever were those shapes, my imput was made for two reasons, for the fallen rocks and the arrastras. With the arrastras i wanted to stimulate some thoughts about how far away could be a mine from the arrastras. From what I have found and I have seen in my all period of treasure hunting, a gold/silver mine to can be operated by group of miners, needs at least five arrastras for the crushing of the ore, with the first till the last to be as possible close to the mine. So I say how if a flat region would been few yards from the mine, then there would been set the arrastras. But a large flat close to a mine is very rare and the miners had to set them around at distances which started from few decades yards to few hundred yards.
I know of two gold mines ( none LDM ) in the vicinity of where Russ is searching, so somewhere there around should be about ten arrastras which could lead someone closer to find them. Usually the one which is in the ruggest region it's the nearest to the mine.
To understand how this works, i will post an aerial image of the arrastras ( yellow circles ) from San Pedro of Tumacacori mine. If you look below the far right arrastra, you can see the path which leads to the mine.