Good find; it was a very compelling read. I'm inclined to believe that apparitions of this sort, as the story-teller supposed, are of a reflective nature; that the beings within, and objects interacted with, are directly related to a certain event or point in time, and thusly are unable to make new actions or even be aware that they are seen. Not two miles from where I now type there is a place called Old Town Spring, which dates back to the 1830s. There are many tales of how our little township was once filled with the sort of vermin Wyatt Earp would later hunt, of ritual cannibalism from one of the local tribe (which I've never believed), and of course, ghosts. We have little tours, even; one stop is the shop for antiques, out of which (and I have heard this, be it a prank or hoax) some nights one can hear music, either from some odd music box or harpsichord, by the sound of it. A bar and grill in the same area, called Wunche, has the top floor sealed off, supposedly due to paranormal activity.
I would suppose that surviving places from those emotionally charged, violent days kept impressions of the people and events which took place therin,
and would further suppose that the same could happen in nature. What draws these impression out for the layman to see, I can only wonder.