My daughter & I were walking the trail today, and I saw this and said, "That is really kewl!" It is a big rootball of a fallen-over tree, that is sprouting all sorts of life! There is grass, bushes, TWO pine trees, and a blackberry bush! Life continues! When searching for this cache, watch the big rootball hole, and there is a scratchy blackberry bush by GZ. I didn't have the heart to do anything to it, because this spot is amazing to me.
Article on Geophysical Observatory
Another blurb about the site